Radiation-sensitive resin composition

ABSTRACT

A radiation-sensitive resin composition comprising (A) a photoacid generator such as
     2,4,6-trimethylphenyldiphenylsulfonium   2,4-difluorobenzenesulfonate or   2,4,6-trimethylphenyldiphenylsulfonium
 
4-trifluoromethylbenzenesulfonate and (B) a resin having an acetal structure typified by a poly(p-hydroxystyrene) resin in which a part of hydrogen atoms of phenolic hydroxyl groups have been replaced by 1-ethoxyethyl groups, 1-ethoxyethyl groups and t-butoxycarbonyl groups, or 1-ethoxyethyl groups and t-butyl groups. The resin composition is sensitive to deep ultraviolet rays and charged particles such as electron beams, exhibits excellent resolution performance and pattern shape-forming capability, and suppresses a nano-edge roughness phenomenon to a minimal extent.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a radiation-sensitive resin compositionuseful as a chemically amplified resist for microfabrication usingvarious radiations, in particular, deep ultraviolet rays such as a KrFexcimer laser and ArF excimer laser, charged particle rays such aselectron beams, and X-rays.

2. Description of the Background Art

In the field of microfabrication exemplified by the manufacture of anintegrated circuit device, development of a lithographic process capableof reproducing microfabrication with a line-width precision of 0.5 μm orless has been pursued in recent years to achieve higher integration. Toensure microfabrication in the order of 0.5 μm or less, a resist whichcan excellently reproduce patterns with a 0.5 μm or less line-width hasbeen required. However, it is difficult to produce such a minute patternat high precision by conventional methods using visible light(wavelength: 800-400 nm) or near ultraviolet light (wavelength: 400-300nm). For this reason, the use of radiation with a shorter wavelength(wavelength: less than 300 nm) has been studied.

As examples of such short wavelength radiation, a bright line spectrumof a mercury lamp (wavelength: 254 nm), deep ultraviolet rays typifiedby a KrF excimer laser (wavelength: 248 nm) and an ArF excimer laser(wavelength: 193 nm), charged particles such as electron beams, andX-rays such as synchrotron radiation can be given. Of these, lithographyusing an excimer laser is regarded as promising due to high output andhigh efficiency. Lithography using an excimer laser requires a resistwhich can reproduce fine patterns with a dimension of 0.5 μm or less athigh sensitivity and high resolution.

Chemically amplified resists comprising a photoacid generator whichforms an acid upon irradiation with radioactive rays (hereinafter called“exposure”) have been proposed as resists applicable to deep ultravioletray such as an excimer laser. The sensitivity of the chemicallyamplified resist is increased by the catalytic action of the acid thusformed.

As such a chemically amplified resist, Japanese Patent ApplicationLaid-open No. 45439/1984 discloses a combination of a resin protectedwith a t-butyl group or a t-butoxycarbonyl group and a photoacidgenerator. Japanese Patent Application Laid-open No. 52845/1985discloses a combination of a resin protected by a silyl group and aphotoacid generator. In addition to these resist compositions, there area number of reports dealing with chemically amplified resists, such as aresist which contains a resin protected by an acetal group or a ketalgroup and a photoacid generator (Japanese Patent Application Laid-openNo. 25850/1990).

Of these chemically amplified resists, those in which a resin having anacetal group or ketal group is used are attracting attention due totheir high resolution capability (e.g. Proc. SPIE Vol. 3049, Page 314).

However, when a stringent line-width control is required such as in thecase of fabricating devices with sub-half micron or less dimensions,resolution capability alone is insufficient. Excellent film surfacesmoothness after formation a resist pattern is also important. If achemically amplified resist exhibiting poor film surface smoothness isused, irregularities (such as nano edge roughness) on the film surfaceis transferred to a substrate when a resist pattern is transferred tothe substrate by an etching process or the like, giving rise to adecrease in dimensional accuracy and impaired electric performance inthe ultimate devices (see, for example, J. Photopolym. Sci. Tech. P 571,1998; Proc. SPIE Vol. 3333, p 313; Proc. SPIE Vol. 3333, p 634; and J.Vac. Sci. Technol. B16(1), 1998, p 69).

Development of a chemically amplified resist exhibiting excellentresolution and only slight nano edge roughness has therefore beendesired.

In more recently, a chemically amplified resist containing a resinhaving an acetal group or a ketal group and one or more compoundsselected from the group consisting of a diazomethane compound,triphenylsulfonium organic sulfonate compound, and diphenyliodoniumorganic sulfonate compound as a photoacid generator was proposed inJapanese Patent Application Laid-open No. 2000-284482. The inventorsclaimed that the resist possesses excellent characteristics such as highsensitivity and resolution capability, and to exhibit only minimalroughness on the pattern sidewalls.

However, development of a photoacid generator used for a chemicallyamplified resist containing a resin having an acetal group or a ketalgroup, particularly a resist exhibiting excellent resolution performanceand small nano-edge roughness, has only just started. Successfuldevelopment of a photoacid generator capable of deriving excellentperformance from this type of chemically amplified resist is stronglydesired from the viewpoint of development of technologies applicable tosemiconductor devices which are increasingly being downsized.

An object of the present invention is to provide a radiation-sensitiveresin composition useful as a chemically-amplified resist, sensitive tovarious radiations, particularly to far ultraviolet rays typified by aKrF excimer laser (wavelength: 248 nm), an ArF excimer laser(wavelength: 193 nm), or an F2 excimer laser (wavelength: 157 nm), aswell as charged particles such as electron beams, exhibiting excellentresolution performance and pattern shape-forming capability, andsuffering from a nano-edge roughness phenomenon only to a minimalextent.

SUMMARY OF THE INVENTION

The above object can be achieved in the present invention by aradiation-sensitive resin composition comprising:

(A) a photoacid generator which is a compound comprising a structureshown by the following formula (1-a) and a structure shown by thefollowing formula (1-b),

wherein the groups R¹ to R¹⁵ individually represent a hydrogen atom, ahydroxyl group, a linear, branched, or cyclic alkyl group having 1-10carbon atoms, a linear, branched, or cyclic alkoxyl group having 1-10carbon atoms, or a t-butoxycarbonylmethoxy group, provided that two ormore of the groups R¹ to R⁵ are groups other than the hydrogen atom, twoor more of the groups R⁶ to R¹⁰ are groups other than the hydrogen atom,or two or more of the groups R¹¹ to R¹⁵ are groups other than thehydrogen atom; and the groups R¹⁶ to R²⁰ individually represent ahydrogen atom, fluorine atom, or trifluoromethyl group, provided that atleast one of the groups R¹⁶ to R²⁰ is a fluorine atom or trifluoromethylgroup, and

(B) a resin comprising a recurring unit shown by the following formula(2),

wherein R²¹ represents a methyl group or ethyl group, and R represents alinear, branched, or cyclic alkyl group having 1-6 carbon atoms, and arecurring unit shown by the following formula (3).

Other objects, features and advantages of the invention will hereinafterbecome more readily apparent from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a drawing illustrating a dimension for evaluating nano-edgeroughness.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS

The present invention will be described in detail below.

Acid Generator (A)

The component (A) of the present invention is a photoacid generatorhaving the structures represented by the above formulas (1-a) and (1-b)(hereinafter referred to as “acid generator (A)”).

Given as examples of the linear, branched, or cyclic alkyl group having1-10 carbon atoms represented by R¹ to R¹⁵ in the formula (1-a) are amethyl group, ethyl group, n-propyl group, i-propyl group, n-butylgroup, i-butyl group, sec-butyl group, t-butyl group, n-pentyl group,neopentyl group, 2-methyl-1-butyl group, 2-methyl-2-butyl group, n-hexylgroup, n-heptyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group,n-decyl group, cyclopentyl group, and cyclohexyl group, and the like.

As examples of the linear, branched, or cyclic alkoxyl group having 1-10carbon atoms represented by R¹ to R¹⁵ are a methoxy group, ethoxy group,n-propoxy group, i-propoxy group, n-butoxy group, i-butoxy group,sec-butoxy group, t-butoxy group, n-pentyloxy group, neopentyloxy group,2-methyl-1-butoxy group, 2-methyl-2-butoxy group, n-hexyloxy group,n-heptyloxy group, n-octyloxy group, 2-ethylhexyloxy group, n-nonyloxygroup, n-decyloxy group, cyclopentyloxy group, and cyclohexyloxy group,and the like.

At least one condition that two or more of the groups R¹ to R⁵ are agroup other than the hydrogen atom, two or more of the groups R⁶ to R¹⁰are a group other than the hydrogen atom, or two or more of the groupsR¹¹ to R¹⁵ are a group other than the hydrogen atom must be satisfied inthe formula (1-a).

In the case where two or more of the groups R¹ to R⁵, two or more of thegroups R⁶ to R¹⁰, or two or more of the groups R¹¹ to R¹⁵ are a groupother than the hydrogen atom, such a group other than the hydrogen atomis preferably a hydroxyl group, methyl group, ethyl group, n-propylgroup, i-propyl group, n-butyl group, i-butyl group, sec-butyl group,t-butyl group, methoxy group, t-butoxy group, or t-butoxycarbonylmethoxygroup, with a particularly preferable group being a methyl group, ethylgroup, i-propyl group, t-butoxy group, or t-butoxycarbonylmethoxy group.

The structure represented by the above formula (1-a) is hereinafterreferred to as a “sulfonium cation (a)” and the structure represented bythe above formula (1-b) is referred to as a “sulfonate anion (b)”.

The following compounds can be given as specific examples of thesulfonium cation (a):

-   2,3-dihydroxyphenyldiphenylsulfonium cation,-   2,4-dihydroxyphenyldiphenylsulfonium cation,-   2,5-dihydroxyphenyldiphenylsulfonium cation,-   2,6-dihydroxyphenyldiphenylsulfonium cation,-   3,4-dihydroxyphenyldiphenylsulfonium cation,-   3,5-dihydroxyphenyldiphenylsulfonium cation,-   2,4,6-trihydroxyphenyldiphenylsulfonium cation,-   2-hydroxy-3-methylphenyldiphenylsulfonium cation,-   2-hydroxy-4-methylphenyldiphenylsulfonium cation,-   2-hydroxy-5-methylphenyldiphenylsulfonium cation,-   2-hydroxy-6-methylphenyldiphenylsulfonium cation,-   3-hydroxy-4-methylphenyldiphenylsulfonium cation,-   3-hydroxy-5-methylphenyldiphenylsulfonium cation,-   2-methyl-3-hydroxyphenyldiphenylsulfonium cation,-   2-methyl-4-hydroxyphenyldiphenylsulfonium cation,-   2-methyl-5-hydroxyphenyldiphenylsulfonium cation,-   3-methyl-4-hydroxyphenyldiphenylsulfonium cation,-   2-hydroxy-3-methoxyphenyldiphenylsulfonium cation,-   2-hydroxy-4-methoxyphenyldiphenylsulfonium cation,-   2-hydroxy-5-methoxyphenyldiphenylsulfonium cation,-   2-hydroxy-6-methoxyphenyldiphenylsulfonium cation,-   3-hydroxy-4-methoxyphenyldiphenylsulfonium cation,-   3-hydroxy-5-methoxyphenyldiphenylsulfonium cation,-   2-methoxy-3-hydroxyphenyldiphenylsulfonium cation,-   2-methoxy-4-hydroxyphenyldiphenylsulfonium cation,-   2-methoxy-5-hydroxyphenyldiphenylsulfonium cation,-   3-methoxy-4-hydroxyphenyldiphenylsulfonium cation,-   2-hydroxy-3-t-butoxyphenyldiphenylsulfonium cation,-   2-hydroxy-4-t-butoxyphenyldiphenylsulfonium cation,-   2-hydroxy-5-t-butoxyphenyldiphenylsulfonium cation,-   2-hydroxy-6-t-butoxyphenyldiphenylsulfonium cation,-   3-hydroxy-4-t-butoxyphenyldiphenylsulfonium cation,-   3-hydroxy-5-t-butoxyphenyldiphenylsulfonium cation,-   2-t-butoxy-3-hydroxyphenyldiphenylsulfonium cation,-   2-t-butoxy-4-hydroxyphenyldiphenylsulfonium cation,-   2-t-butoxy-5-hydroxyphenyldiphenylsulfonium cation,-   3-t-butoxy-4-hydroxyphenyldiphenylsulfonium cation,-   2-hydroxy-3-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   2-hydroxy-4-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   2-hydroxy-5-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   2-hydroxy-6-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   3-hydroxy-4-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   3-hydroxy-5-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   2-t-butoxycarbonylmethoxy-3-hydroxyphenyldiphenylsulfonium cation,-   2-t-butoxycarbonylmethoxy-4-hydroxyphenyldiphenylsulfonium cation,-   2-t-butoxycarbonylmethoxy-5-hydroxyphenyldiphenylsulfonium cation,-   3-t-butoxycarbonylmethoxy-4-hydroxyphenyldiphenylsulfonium cation,-   2,3-dimethylphenyldiphenylsulfonium cation,-   2,4-dimethylphenyldiphenylsulfonium cation,-   2,5-dimethylphenyldiphenylsulfonium cation,-   2,6-dimethylphenyldiphenylsulfonium cation,-   3,4-dimethylphenyldiphenylsulfonium cation,-   3,5-dimethylphenyldiphenylsulfonium cation,-   2,4,6-trimethylphenyldiphenylsulfonium cation,-   2,3-diethylphenyldiphenylsulfonium cation,-   2,4-diethylphenyldiphenylsulfonium cation,-   2,5-diethylphenyldiphenylsulfonium cation,-   2,6-diethylphenyldiphenylsulfonium cation,-   3,4-diethylphenyldiphenylsulfonium cation,-   3,5-diethylphenyldiphenylsulfonium cation,-   2,4,6-triethylphenyldiphenylsulfonium cation,-   2,4-di-n-propylphenyldiphenylsulfonium cation,-   2,4,6-tri-n-propylphenyldiphenylsulfonium cation,-   2,4-di-i-propylphenyldiphenylsulfonium cation,-   2,4,6-tri-i-propylphenyldiphenylsulfonium cation,-   2,4-di-n-butylphenyldiphenylsulfonium cation,-   2,4,6-tri-n-butylphenyldiphenylsulfonium cation,-   2,4-di-i-butylphenyldiphenylsulfonium cation,-   2,4,6-tri-i-butylphenyldiphenylsulfonium cation,-   2,4-di-sec-butylphenyldiphenylsulfonium cation,-   2,4,6-tri-sec-butylphenyldiphenylsulfonium cation,-   2,4-di-t-butylphenyldiphenylsulfonium cation,-   2,4,6-tri-t-butylphenyldiphenylsulfonium cation,-   2-methyl-4-n-propylphenyldiphenylsulfonium cation,-   2-methyl-4-i-propylphenyldiphenylsulfonium cation,-   2-methyl-4-n-butylphenyldiphenylsulfonium cation,-   2-methyl-4-t-butylphenyldiphenylsulfonium cation,-   2-methyl-4-n-hexylphenyldiphenylsulfonium cation,-   2-methyl-4-n-octylphenyldiphenylsulfonium cation,-   2-methyl-4-n-decylphenyldiphenylsulfonium cation,-   2-methyl-4-n-cyclohexylphenyldiphenylsulfonium cation,-   2-methyl-3-methoxyphenyldiphenylsulfonium cation,-   2-methyl-4-methoxyphenyldiphenylsulfonium cation,-   2-methyl-5-methoxyphenyldiphenylsulfonium cation,-   2-methyl-6-methoxyphenyldiphenylsulfonium cation,-   3-methyl-4-methoxyphenyldiphenylsulfonium cation,-   3-methyl-5-methoxyphenyldiphenylsulfonium cation,-   2-methoxy-3-methylphenyldiphenylsulfonium cation,-   2-methoxy-4-methylphenyldiphenylsulfonium cation,-   2-methoxy-5-methylphenyldiphenylsulfonium cation,-   3-methoxy-4-methylphenyldiphenylsulfonium cation,-   2-methyl-4-n-propoxyphenyldiphenylsulfonium cation,-   2-methyl-4-i-propoxyphenyldiphenylsulfonium cation,-   2-methyl-4-n-butoxyphenyldiphenylsulfonium cation,-   2-methyl-4-n-hexyloxyphenyldiphenylsulfonium cation,-   2-methyl-4-n-octyloxyphenyldiphenylsulfonium cation,-   2-methyl-4-n-decyloxyphenyldiphenylsulfonium cation,-   2-methyl-4-cyclohexyloxyphenyldiphenylsulfonium cation,-   2-methyl-3-t-butoxyphenyldiphenylsulfonium cation,-   2-methyl-4-t-butoxyphenyldiphenylsulfonium cation,-   2-methyl-5-t-butoxyphenyldiphenylsulfonium cation,-   2-methyl-6-t-butoxyphenyldiphenylsulfonium cation,-   3-methyl-4-t-butoxyphenyldiphenylsulfonium cation,-   3-methyl-5-t-butoxyphenyldiphenylsulfonium cation,-   2-t-butoxy-3-methylphenyldiphenylsulfonium cation,-   2-t-butoxy-4-methylphenyldiphenylsulfonium cation,-   2-t-butoxy-5-methylphenyldiphenylsulfonium cation,-   3-t-butoxy-4-methylphenyldiphenylsulfonium cation,-   4-t-butoxy-2,6-dimethylphenyldiphenylsulfonium cation,-   2-methyl-3-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   2-methyl-4-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   2-methyl-5-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   2-methyl-6-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   3-methyl-4-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   3-methyl-5-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   2-t-butoxycarbonylmethoxy-3-methylphenyldiphenylsulfonium cation,-   2-t-butoxycarbonylmethoxy-4-methylphenyldiphenylsulfonium cation,-   2-t-butoxycarbonylmethoxy-5-methylphenyldiphenylsulfonium cation,-   3-t-butoxycarbonylmethoxy-4-methylphenyldiphenylsulfonium cation,-   4-t-butoxycarbonylmethoxy-2,6-dimethylphenyldiphenylsulfonium    cation,-   2,3-dimethoxyphenyldiphenylsulfonium cation,-   2,4-dimethoxyphenyldiphenylsulfonium cation,-   2,5-dimethoxyphenyldiphenylsulfonium cation,-   2,6-dimethoxyphenyldiphenylsulfonium cation,-   3,4-dimethoxyphenyldiphenylsulfonium cation,-   3,5-dimethoxyphenyldiphenylsulfonium cation,-   2,4,6-trimethoxyphenyldiphenylsulfonium cation,-   2-methoxy-3-t-butoxyphenyldiphenylsulfonium cation,-   2-methoxy-4-t-butoxyphenyldiphenylsulfonium cation,-   2-methoxy-5-t-butoxyphenyldiphenylsulfonium cation,-   2-methoxy-6-t-butoxyphenyldiphenylsulfonium cation,-   3-methoxy-4-t-butoxyphenyldiphenylsulfonium cation,-   3-methoxy-5-t-butoxyphenyldiphenylsulfonium cation,-   2-t-butoxy-3-methoxyphenyldiphenylsulfonium cation,-   2-t-butoxy-4-methoxyphenyldiphenylsulfonium cation,-   2-t-butoxy-5-methoxyphenyldiphenylsulfonium cation,-   3-t-butoxy-4-methoxyphenyldiphenylsulfonium cation,-   2,3-di-t-butoxyphenyldiphenylsulfonium cation,-   2,4-di-t-butoxyphenyldiphenylsulfonium cation,-   2,5-di-t-butoxyphenyldiphenylsulfonium cation,-   2,6-di-t-butoxyphenyldiphenylsulfonium cation,-   3,4-di-t-butoxyphenyldiphenylsulfonium cation,-   3,5-di-t-but oxyphenyldiphenylsulfonium cation,-   2,4,6-tri-t-butoxyphenyldiphenylsulfonium cation,-   2-methoxy-3-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   2-methoxy-4-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   2-methoxy-5-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   2-methoxy-6-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   3-methoxy-4-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   3-methoxy-5-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   2-t-butoxycarbonylmethoxy-3-methoxyphenyldiphenylsulfonium cation,-   2-t-butoxycarbonylmethoxy-4-methoxyphenyldiphenylsulfonium cation,-   2-t-butoxycarbonylmethoxy-5-methoxyphenyldiphenylsulfonium cation,-   3-t-butoxycarbonylmethoxy-4-methoxyphenyldiphenylsulfonium cation,-   2-t-butoxy-3-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   2-t-butoxy-4-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   2-t-butoxy-5-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   2-t-butoxy-6-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   3-t-butoxy-4-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   3-t-butoxy-5-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   2-t-butoxycarbonylmethoxy-3-t-butoxyphenyldiphenylsulfonium cation,-   2-t-butoxycarbonylmethoxy-4-t-butoxyphenyldiphenylsulfonium cation,-   2-t-butoxycarbonylmethoxy-5-t-butoxyphenyldiphenylsulfonium cation,-   3-t-butoxycarbonylmethoxy-4-t-butoxyphenyldiphenylsulfonium cation,-   2,3-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   2,4-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   2,5-di-t-butoxymethoxyphenyldiphenylsulfonium cation,-   2,6-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   3,4-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   3,5-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   2,4,6-tri-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   phenylbis(2,3-dimethylphenyl)sulfonium cation,-   phenylbis(2,4-dimethylphenyl)sulfonium cation,-   phenylbis(2,5-dimethylphenyl)sulfonium cation,-   phenylbis(2,6-dimethylphenyl)sulfonium cation,-   phenylbis(3,4-dimethylphenyl)sulfonium cation,-   phenylbis(3,5-dimethylphenyl)sulfonium cation,-   phenylbis(2,4,6-trimethylphenyl)sulfonium cation,-   tris(2,3-dimethylphenyl)sulfonium cation,-   tris(2,4-dimethylphenyl)sulfonium cation,-   tris(2,5-dimethylphenyl)sulfonium cation,-   tris(2,6-dimethylphenyl)sulfonium cation,-   tris(3,4-dimethylphenyl)sulfonium cation,-   tris(3,5-dimethylphenyl)sulfonium cation, and-   tris(2,4,6-trimethylphenyl)sulfonium cation.

Of these sulfonium cations (a), the following compounds are preferable:

-   2,4-dihydroxyphenyldiphenylsulfonium cation,-   2,4-dimethylphenyldiphenylsulfonium cation,-   2,6-dimethylphenyldiphenylsulfonium cation,-   2,4,6-trimethylphenyldiphenylsulfonium cation,-   2,4,6-triethylphenyldiphenylsulfonium cation,-   2,4,6-tri-i-propylphenyldiphenylsulfonium cation,-   2,4-di-t-butoxyphenyldiphenylsulfonium cation,-   2,4-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,-   4-t-butoxy-2,6-dimethylphenyldiphenylsulfonium cation, and-   4-t-butoxycarbonylmethoxy-2,6-dimethylphenyldiphenylsulfonium    cation.

In the formula (1-b), preferable groups represented by R¹⁶ to R²⁰ are afluorine atom and trifluoromethyl group, and the total number of thefluorine atom and trifluoromethyl group represented by R¹⁶ to R²⁰ is1-5.

The following compounds can be given as specific examples of thesulfonate anion (b):

-   2-fluorobenzenesulfonate anion,-   3-fluorobenzenesulfonate anion,-   4-fluorobenzenesulfonate anion,-   2,3-difluorobenzenesulfonate anion,-   2,4-difluorobenzenesulfonate anion,-   2,5-difluorobenzenesulfonate anion,-   2,6-difluorobenzenesulfonate anion,-   3,2-difluorobenzenesulfonate anion,-   3,5-difluorobenzenesulfonate anion,-   2,4,6-trifluorobenzenesulfonate anion,-   2,3,5,6-tetrafluorobenzenesulfonate anion,-   2,3,4,5,6-pentafluorobenzenesulfonate anion,-   2-fluoro-3-trifluoromethylbenzenesulfonate anion,-   2-fluoro-4-trifluoromethylbenzenesulfonate anion,-   2-fluoro-5-trifluoromethylbenzenesulfonate anion,-   2-fluoro-6-trifluoromethylbenzenesulfonate anion,-   3-fluoro-4-trifluoromethylbenzenesulfonate anion,-   3-fluoro-5-trifluoromethylbenzenesulfonate anion,-   2-trifluoromethyl-3-fluorobenzenesulfonate anion,-   2-trifluoromethyl-4-fluorobenzenesulfonate anion,-   2-trifluoromethyl-5-fluorobenzenesulfonate anion,-   3-trifluoromethyl-4-fluorobenzenesulfonate anion,-   2-trifluoromethylbenzenesulfonate anion,-   3-trifluoromethylbenzenesulfonate anion,-   4-trifluoromethylbenzenesulfonate anion,-   2,3-bis(trifluoromethyl)benzenesulfonate anion,-   2,4-bis(trifluoromethyl)benzenesulfonate anion,-   2,5-bis(trifluoromethyl)benzenesulfonate anion,-   2,6-bis(trifluoromethyl)benzenesulfonate anion,-   3,4-bis(trifluoromethyl)benzenesulfonate anion,-   3,5-bis(trifluoromethyl)benzenesulfonate anion,-   2,4,6-tris(trifluoromethyl)benzenesulfonate anion,-   2,3,5,6-tetrakis(trifluoromethyl)benzenesulfonate anion, and-   2,3,4,5,6-pentakis(trifluoromethyl)benzenesulfonate anion.

Of these sulfonate anions (b), the following compounds are preferable:

-   4-fluorobenzenesulfonate anion,-   2,4-difluorobenzenesulfonate anion,-   2,6-difluorobenzenesulfonate anion,-   2,3,4,5,6-pentafluorobenzenesulfonate anion,-   4-trifluoromethylbenzenesulfonate anion,-   2,4-bis(trifluoromethyl)benzenesulfonate anion,-   2,4,6-tris(trifluoromethyl)benzenesulfonate anion, and-   2,3,4,5,6-pentakis(trifluoromethyl)benzenesulfonate anion.

The following compounds can be given as examples of the acid generator(A) preferably used in the present invention:

-   2,4-dihydroxyphenyldiphenylsulfonium 4-fluorobenzenesulfonate,-   2,4-dihydroxyphenyldiphenylsulfonium 2,4-difluorobenzenesulfonate,-   2,4-dihydroxyphenyldiphenylsulfonium 2,6-difluorobenzenesulfonate,-   2,4-dihydroxyphenyldiphenylsulfonium    2,3,4,5,6-pentafluorobenzenesulfonate,-   2,4-dihydroxyphenyldiphenylsulfonium    4-trifluoromethylbenzenesulfonate,-   2,4-dihydroxyphenyldiphenylsulfonium    2,4-bis(trifluoromethyl)benzenesulfonate,-   2,4-dihydroxyphenyldiphenylsulfonium    2,4,6-tris(trifluoromethyl)benzenesulfonate,-   2,4-dihydroxyphenyldiphenylsulfonium    2,3,4,5,6-pentakis(trifluoromethyl)benzenesulfonate,-   2,4-dimethylphenyldiphenylsulfonium 4-fluorobenzenesulfonate,-   2,4-dimethylphenyldiphenylsulfonium 2,4-difluorobenzenesulfonate,-   2,4-dimethylphenyldiphenylsulfonium 2,6-difluorobenzenesulfonate,-   2,4-dimethylphenyldiphenylsulfonium    2,3,4,5,6-pentafluorobenzenesulfonate,-   2,4-dimethylphenyldiphenylsulfonium    4-trifluoromethylbenzenesulfonate,-   2,4-dimethylphenyldiphenylsulfonium    2,4-bis(trifluoromethyl)benzenesulfonate,-   2,4-dimethylphenyldiphenylsulfonium    2,4,6-tris(trifluoromethyl)benzenesulfonate,-   2,4-dimethylphenyldiphenylsulfonium    2,3,4,5,6-pentakis(trifluoromethyl)benzenesulfonate,-   2,6-dimethylphenyldiphenylsulfonium 4-fluorobenzenesulfonate,-   2,6-dimethylphenyldiphenylsulfonium 2,4-difluorobenzenesulfonate,-   2,6-dimethylphenyldiphenylsulfonium 2,6-difluorobenzenesulfonate,-   2,6-dimethylphenyldiphenylsulfonium    2,3,4,5,6-pentafluorobenzenesulfonate,-   2,6-dimethylphenyldiphenylsulfonium    4-trifluoromethylbenzenesulfonate,-   2,6-dimethylphenyldiphenylsulfonium    2,4-bis(trifluoromethyl)benzenesulfonate,-   2,6-dimethylphenyldiphenylsulfonium    2,4,6-tris(trifluoromethyl)benzenesulfonate,-   2,6-dimethylphenyldiphenylsulfonium    2,3,4,5,6-pentakis(trifluoromethyl)benzenesulfonate,-   3,5-dimethylphenyldiphenylsulfonium 4-fluorobenzenesulfonate,-   3,5-dimethylphenyldiphenylsulfonium 2,4-difluorobenzenesulfonate,-   3,5-dimethylphenyldiphenylsulfonium 2,6-difluorobenzenesulfonate,-   3,5-dimethylphenyldiphenylsulfonium    2,3,4,5,6-pentafluorobenzenesulfonate,-   3,5-dimethylphenyldiphenylsulfonium    4-trifluoromethylbenzenesulfonate,-   3,5-dimethylphenyldiphenylsulfonium    2,4-bis(trifluoromethyl)benzenesulfonate,-   3,5-dimethylphenyldiphenylsulfonium    2,4,6-tris(trifluoromethyl)benzenesulfonate,-   3,5-dimethylphenyldiphenylsulfonium    2,3,4,5,6-pentakis(trifluoromethyl)benzenesulfonate,-   2,4,6-trimethylphenyldiphenylsulfonium 4-fluorobenzenesulfonate,-   2,4,6-trimethylphenyldiphenylsulfonium 2,4-difluorobenzenesulfonate,-   2,4,6-trimethylphenyldiphenylsulfonium 2,6-difluorobenzenesulfonate,-   2,4,6-trimethylphenyldiphenylsulfonium    2,3,4,5,6-pentafluorobenzenesulfonate,-   2,4,6-trimethylphenyldiphenylsulfonium    4-trifluoromethylbenzenesulfonate,-   2,4,6-trimethylphenyldiphenylsulfonium    2,4-bis(trifluoromethyl)benzenesulfonate,-   2,4,6-trimethylphenyldiphenylsulfonium    2,4,6-tris(trifluoromethyl)benzenesulfonate,-   2,4,6-trimethylphenyldiphenylsulfonium    2,3,4,5,6-pentakis(trifluoromethyl)benzenesulfonate,-   2,4,6-triethylphenyldiphenylsulfonium 4-fluorobenzenesulfonate,-   2,4,6-triethylphenyldiphenylsulfonium 2,4-difluorobenzenesulfonate,-   2,4,6-triethylphenyldiphenylsulfonium 2,6-difluorobenzenesulfonate,-   2,4,6-triethylphenyldiphenylsulfonium    2,3,4,5,6-pentafluorobenzenesulfonate,-   2,4,6-triethylphenyldiphenylsulfonium    4-trifluoromethylbenzenesulfonate,-   2,4,6-triethylphenyldiphenylsulfonium    2,4-bis(trifluoromethyl)benzenesulfonate,-   2,4,6-triethylphenyldiphenylsulfonium    2,4,6-tris(trifluoromethyl)benzenesulfonate,-   2,4,6-triethylphenyldiphenylsulfonium    2,3,4,5,6-pentakis(trifluoromethyl)benzenesulfonate,-   2,4,6-tri-i-propylphenyldiphenyl sulfonium 4-fluorobenzenesulfonate,-   2,4,6-tri-i-propylphenyldiphenyl sulfonium    2,4-difluorobenzenesulfonate,-   2,4,6-tri-i-propylphenyldiphenyl sulfonium    2,6-difluorobenzenesulfonate,-   2,4,6-tri-i-propylphenyldiphenylsulfonium    2,3,4,5,6-pentafluorobenzenesulfonate,-   2,4,6-tri-i-propylphenyldiphenyl sulfonium    4-trifluoromethylbenzenesulfonate,-   2,4,6-tri-i-propylphenyldiphenylsulfonium    2,4-bis(trifluoromethyl)benzenesulfonate,-   2,4,6-tri-i-propylphenyldiphenylsulfonium    2,4,6-tris(trifluoromethyl)benzenesulfonate,-   2,4,6-tri-i-propylphenyldiphenylsulfonium    2,3,4,5,6-pentakis(trifluoromethyl)benzenesulfonate,-   2,4-di-t-butoxyphenyldiphenylsulfonium 4-fluorobenzenesulfonate,-   2,4-di-t-butoxyphenyldiphenylsulfonium 2,4-difluorobenzenesulfonate,-   2,4-di-t-butoxyphenyldiphenylsulfonium 2,6-difluorobenzenesulfonate,-   2,4-di-t-butoxyphenyldiphenylsulfonium    2,3,4,5,6-pentafluorobenzenesulfonate,-   2,4-di-t-butoxyphenyldiphenylsulfonium    4-trifluoromethylbenzenesulfonate,-   2,4-di-t-butoxyphenyldiphenylsulfonium    2,4-bis(trifluoromethyl)benzenesulfonate,-   2,4-di-t-butoxyphenyldiphenylsulfonium    2,4,6-tris(trifluoromethyl)benzenesulfonate,-   2,4-di-t-butoxyphenyldiphenylsulfonium    2,3,4,5,6-pentakis(trifluoromethyl)benzenesulfonate,-   2,6-di-t-butoxyphenyldiphenylsulfonium 4-fluorobenzenesulfonate,-   2,6-di-t-butoxyphenyldiphenylsulfonium 2,4-difluorobenzenesulfonate,-   2,6-di-t-butoxyphenyldiphenylsulfonium 2,6-difluorobenzenesulfonate,-   2,6-di-t-butoxyphenyldiphenylsulfonium    2,3,4,5,6-pentafluorobenzenesulfonate,-   2,6-di-t-butoxyphenyldiphenylsulfonium    4-trifluoromethylbenzenesulfonate,-   2,6-di-t-butoxyphenyldiphenylsulfonium    2,4-bis(trifluoromethyl)benzenesulfonate,-   2,6-di-t-butoxyphenyldiphenylsulfonium    2,4,6-tris(trifluoromethyl)benzenesulfonate,-   2,6-di-t-butoxyphenyldiphenylsulfonium    2,3,4,5,6-pentakis(trifluoromethyl)benzenesulfonate,-   3,5-di-t-butoxyphenyldiphenylsulfonium 4-fluorobenzenesulfonate,-   3,5-di-t-butoxyphenyldiphenylsulfonium 2,4-difluorobenzenesulfonate,-   3,5-di-t-butoxyphenyldiphenylsulfonium 2,6-difluorobenzenesulfonate,-   3,5-di-t-butoxyphenyldiphenylsulfonium    2,3,4,5,6-pentafluorobenzenesulfonate,-   3,5-di-t-butoxyphenyldiphenylsulfonium    4-trifluoromethylbenzenesulfonate,-   3,5-di-t-butoxyphenyldiphenylsulfonium    2,4-bis(trifluoromethyl)benzenesulfonate,-   3,5-di-t-butoxyphenyldiphenylsulfonium    2,4,6-tris(trifluoromethyl)benzenesulfonate,-   3,5-di-t-butoxyphenyldiphenylsulfonium    2,3,4,5,6-pentakis(trifluoromethyl)benzenesulfonate,-   2,4,6-tri-t-butoxyphenyldiphenylsulfonium 4-fluorobenzenesulfonate,-   2,4,6-tri-t-butoxyphenyldiphenylsulfonium    2,4-difluorobenzenesulfonate,-   2,4,6-tri-t-butoxyphenyldiphenylsulfonium    2,6-difluorobenzenesulfonate,-   2,4,6-tri-t-butoxyphenyldiphenylsulfonium    2,3,4,5,6-pentafluorobenzenesulfonate,-   2,4,6-tri-t-butoxyphenyldiphenylsulfonium    4-trifluoromethylbenzenesulfonate,-   2,4,6-tri-t-butoxyphenyldiphenylsulfonium    2,4-bis(trifluoromethyl)benzenesulfonate,-   2,4,6-tri-t-butoxyphenyldiphenylsulfonium    2,4,6-tris(trifluoromethyl)benzenesulfonate,-   2,4,6-tri-t-butoxyphenyldiphenylsulfonium    2,3,4,5,6-pentakis(trifluoromethyl)benzenesulfonate,-   2,4-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    4-fluorobenzenesulfonate,-   2,4-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,4-difluorobenzenesulfonate,-   2,4-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,6-difluorobenzenesulfonate,-   2,4-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,3,4,5,6-pentafluorobenzenesulfonate,-   2,4-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    4-trifluoromethylbenzenesulfonate,-   2,4-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,4-bis(trifluoromethyl)benzenesulfonate,-   2,4-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,4,6-tris(trifluoromethyl)benzenesulfonate,-   2,4-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,3,4,5,6-pentakis(trifluoromethyl)benzenesulfonate,-   2,6-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    4-fluorobenzenesulfonate,-   2,6-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,4-difluorobenzenesulfonate,-   2,6-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,6-difluorobenzenesulfonate,-   2,6-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,3,4,5,6-pentafluorobenzenesulfonate,-   2,6-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    4-trifluoromethylbenzenesulfonate,-   2,6-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,4-bis(trifluoromethyl)benzenesulfonate,-   2,6-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,4,6-tris(trifluoromethyl)benzenesulfonate,-   2,6-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,3,4,5,6-pentakis(trifluoromethyl)benzenesulfonate,-   3,5-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    4-fluorobenzenesulfonate,-   3,5-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,4-difluorobenzenesulfonate,-   3,5-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,6-difluorobenzenesulfonate,-   3,5-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,3,4,5,6-pentafluorobenzenesulfonate,-   3,5-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    4-trifluoromethylbenzenesulfonate,-   3,5-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,4-bis(trifluoromethyl)benzenesulfonate,-   3,5-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,4,6-tris(trifluoromethyl)benzenesulfonate,-   3,5-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,3,4,5,6-pentakis(trifluoromethyl)benzenesulfonate,-   2,4,6-tri-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    4-fluorobenzenesulfonate,-   2,4,6-tri-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,4-difluorobenzenesulfonate,-   2,4,6-tri-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,6-difluorobenzenesulfonate,-   2,4,6-tri-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,3,4,5,6-pentafluorobenzenesulfonate,-   2,4,6-tri-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    4-trifluoromethylbenzenesulfonate,-   2,4,6-tri-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,4-bis(trifluoromethyl)benzenesulfonate,-   2,4,6-tri-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,4,6-tris(trifluoromethyl)benzenesulfonate,-   2,4,6-tri-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,3,4,5,6-pentakis(trifluoromethyl)benzenesulfonate,-   4-t-butoxy-2,6-dimethylphenyldiphenylsulfonium    4-fluorobenzenesulfonate,-   4-t-butoxy-2,6-dimethylphenyldiphenylsulfonium    2,4-difluorobenzenesulfonate,-   4-t-butoxy-2,6-dimethylphenyldiphenylsulfonium    2,6-difluorobenzenesulfonate,-   4-t-butoxy-2,6-dimethylphenyldiphenylsulfonium    2,3,4,5,6-pentafluorobenzenesulfonate,-   4-t-butoxy-2,6-dimethylphenyldiphenylsulfonium    4-trifluoromethylbenzenesulfonate,-   4-t-butoxy-2,6-dimethylphenyldiphenylsulfonium    2,4-bis(trifluoromethyl)benzenesulfonate,-   4-t-butoxy-2,6-dimethylphenyldiphenylsulfonium    2,4,6-tris(trifluoromethyl)benzenesulfonate,-   4-t-butoxy-2,6-dimethylphenyldiphenylsulfonium    2,3,4,5,6-pentakis(trifluoromethyl)benzenesulfonate,-   4-t-butoxycarbonylmethoxy-2,6-dimethylphenyldiphenylsulfonium    4-fluorobenzenesulfonate,-   4-t-butoxycarbonylmethoxy-2,6-dimethylphenyldiphenylsulfonium    2,4-difluorobenzenesulfonate,-   4-t-butoxycarbonylmethoxy-2,6-dimethylphenyldiphenylsulfonium    2,6-difluorobenzenesulfonate,-   4-t-butoxycarbonylmethoxy-2,6-dimethylphenyldiphenylsulfonium    2,3,4,5,6-pentafluorobenzenesulfonate,-   4-t-butoxycarbonylmethoxy-2,6-dimethylphenyldiphenylsulfonium    4-trifluoromethylbenzenesulfonate,-   4-t-butoxycarbonylmethoxy-2,6-dimethylphenyldiphenylsulfonium    2,4-bis(trifluoromethyl)benzenesulfonate,-   4-t-butoxycarbonylmethoxy-2,6-dimethylphenyldiphenylsulfonium    2,4,6-tris(trifluoromethyl)benzenesulfonate,-   and 4-t-butoxycarbonylmethoxy-2,6-dimethylphenyldiphenylsulfonium,    and-   2,3,4,5,6-pentakis(trifluoromethyl)benzenesulfonate.

Of these acid generators (A), the following compounds are particularlypreferable:

-   2,4-dihydroxyphenyldiphenylsulfonium    2,4,6-tris(trifluoromethyl)benzenesulfonate,-   2,4-dimethylphenyldiphenylsulfonium    2,3,4,5,6-pentakis(trifluoromethyl)benzenesulfonate,-   2,4,6-trimethylphenyldiphenylsulfonium 2,4-difluorobenzenesulfonate,-   2,4,6-trimethylphenyldiphenylsulfonium    4-trifluoromethylbenzenesulfonate,-   2,4,6-triethylphenyldiphenylsulfonium    4-trifluoromethylbenzenesulfonate,-   2,4,6-tri-i-propylphenyldiphenyl sulfonium    2,4-difluorobenzenesulfonate,-   4-t-butoxy-2,6-dimethylphenyldiphenylsulfonium    2,3,4,5,6-pentafluorobenzenesulfonate,-   and 4-t-butoxycarbonylmethoxy-2,6-dimethylphenyldiphenylsulfonium    2,4,6-tris(trifluoromethyl)benzenesulfonate.    Other Acid Generators

In the present invention, the following photoacid generators(hereinafter referred to as “other acid generators”) can optionally beused in combination with the acid generator (A).

As examples of the other acid generators, (1) onium salt compounds, (2)sulfone compounds, (3) sulfonate compounds, (4) sulfonimide compounds,(5) diazomethane compounds, (6) oxime sulfonate compounds, and the likecan be given. These other acid generators will now be described indetail.

(1) Onium Salt Compounds

As examples of onium salt compounds, iodonium salt, sulfonium salt,phosphonium salt, diazonium salt, ammonium salt, pyridinium salt, andthe like can be given.

Specific examples of onium salts include:

-   bis(p-t-butylphenyl)iodoniumtrifluoromethane sulfonate,-   bis(p-t-butylphenyl)iodonium nonafluoro-n-butanesulfonate,-   bis(p-t-butylphenyl)iodonium o-trifluoromethylbenzenesulfonate,-   bis(p-t-butylphenyl)iodonium p-trifluoromethylbenzenesulfonate,-   bis(p-t-butylphenyl)iodonium 10-camphorsulfonate,-   bis(p-t-butylphenyl)iodonium p-toluenesulfonate,-   bis(p-t-butylphenyl)iodonium pyrenesulfonate,-   bis(p-t-butylphenyl)iodonium n-dodecylbenzenesulfonate,-   bis(p-t-butylphenyl)iodonium benzenesulfonate,-   bis(p-t-butylphenyl)iodonium 2,4-difluorobenzenesulfonate,-   bis(p-t-butylphenyl)iodonium n-octanesulfonate,-   diphenyliodonium trifluoromethanesulfonate,-   diphenyliodonium nonafluoro-n-butanesulfonate,-   diphenyliodonium o-trifluoromethylbenzenesulfonate,-   diphenyliodonium p-trifluoromethylbenzenesulfonate,-   diphenyliodonium 10-camphorsulfonate,-   diphenyliodonium p-toluenesulfonate,-   diphenyliodonium pyrenesulfonate,-   diphenyliodonium n-dodecylbenzenesulfonate,-   diphenyliodonium benzenesulfonate,-   triphenylsulfonium 2,4-difluorobenzenesulfonate,-   diphenyliodonium n-oactanesulfonate,-   triphenylsulfonium trifluoromethanesulfonate,-   triphenylsulfonium nonafluoro-n-butanesulfonate,-   triphenylsulfonium o-trifluoromethylbenzenesulfonate,-   triphenylsulfonium p-trifluoromethylbenzenesulfonate,-   triphenylsulfonium 10-camphorsulfonate,-   triphenylsulfonium p-toluenesulfonate,-   triphenylsulfonium pyrenesulfonate,-   triphenylsulfonium n-dodecylbenzenesulfonate,-   triphenylsulfonium benzenesulfonate,-   triphenylsulfonium 2,4-difluorobenzenesulfonate,-   triphenylsulfonium n-oactanesulfonate,-   p-methylphenyldiphenylsulfonium trifluoromethanesulfonate,-   p-methylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate,-   p-methylphenyldiphenylsulfonium o-trifluoromethylbenzenesulfonate,-   p-methylphenyldiphenylsulfonium p-trifluoromethylbenzenesulfonate,-   p-methylphenyldiphenylsulfonium 10-camphorsulfonate,-   p-methylphenyldiphenylsulfonium p-toluenesulfonate,-   p-methylphenyldiphenylsulfonium pyrenesulfonate,-   p-methylphenyldiphenylsulfonium n-dodecylbenzenesulfonate,-   p-methylphenyldiphenylsulfonium benzenesulfonate,-   p-methylphenyldiphenylsulfonium 2,4-difluorobenzenesulfonate,-   p-methylphenyldiphenylsulfonium n-octanesulfonate,-   p-ethylphenyldiphenylsulfonium trifluoromethanesulfonate,-   p-ethylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate,-   p-ethylphenyldiphenylsulfonium o-trifluoromethylbenzenesulfonate,-   p-ethylphenyldiphenylsulfonium p-trifluoromethylbenzenesulfonate,-   p-ethylphenyldiphenylsulfonium 10-camphorsulfonate,-   p-ethylphenyldiphenylsulfonium p-toluenesulfonate,-   p-ethylphenyldiphenylsulfonium pyrenesulfonate,-   p-ethylphenyldiphenylsulfonium n-dodecylbenzenesulfonate,-   p-ethylphenyldiphenylsulfonium benzenesulfonate,-   p-ethylphenyldiphenylsulfonium 2,4-difluorobenzenesulfonate,-   p-ethylphenyldiphenylsulfonium n-octanesulfonate,-   p-i-propylphenyldiphenylsulfonium trifluoromethanesulfonate,-   p-i-propylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate,-   p-i-propylphenyldiphenylsulfonium o-trifluoromethylbenzenesulfonate,-   p-i-propylphenyldiphenylsulfonium p-trifluoromethylbenzenesulfonate,-   p-i-propylphenyldiphenylsulfonium 10-camphorsulfonate,-   p-i-propylphenyldiphenylsulfonium p-toluenesulfonate,-   p-i-propylphenyldiphenylsulfonium pyrenesulfonate,-   p-i-propylphenyldiphenylsulfonium n-dodecylbenzenesulfonate,-   p-i-propylphenyldiphenylsulfonium benzenesulfonate,-   p-i-propylphenyldiphenylsulfonium 2,4-difluorobenzenesulfonate,-   p-i-propylphenyldiphenylsulfonium n-octanesulfonate,-   p-t-butylphenyldiphenylsulfonium trifluoromethanesulfonate,-   p-t-butylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate,-   p-t-butylphenyldiphenylsulfonium o-trifluoromethylbenzenesulfonate,-   p-t-butylphenyldiphenylsulfonium p-trifluoromethylbenzenesulfonate,-   p-t-butylphenyldiphenylsulfonium 10-camphorsulfonate,-   p-t-butylphenyldiphenylsulfonium p-toluenesulfonate,-   p-t-butylphenyldiphenylsulfonium pyrenesulfonate,-   p-t-butylphenyldiphenylsulfonium n-dodecylbenzenesulfonate,-   p-t-butylphenyldiphenylsulfonium benzenesulfonate,-   p-t-butylphenyldiphenylsulfonium 2,4-difluorobenzenesulfonate,-   p-t-butylphenyldiphenylsulfonium n-octanesulfonate,-   p-methoxyphenyldiphenylsulfonium trifluoromethanesulfonate,-   p-methoxyphenyldiphenylsulfonium nonafluoro-n-butanesulfonate,-   p-methoxyphenyldiphenylsulfonium o-trifluoromethylbenzenesulfonate,-   p-methoxyphenyldiphenylsulfonium p-trifluoromethylbenzenesulfonate,-   p-methoxyphenyldiphenylsulfonium 10-camphorsulfonate,-   p-methoxyphenyldiphenylsulfonium p-toluenesulfonate,-   p-methoxyphenyldiphenylsulfonium pyrenesulfonate,-   p-methoxyphenyldiphenylsulfonium n-dodecylbenzenesulfonate,-   p-methoxyphenyldiphenylsulfonium benzenesulfonate,-   p-methoxyphenyldiphenylsulfonium 2,4-difluorobenzenesulfonate,-   p-methoxyphenyldiphenylsulfonium n-octanesulfonate,-   p-t-butoxyphenyldiphenylsulfonium trifluoromethanesulfonate,-   p-t-butoxyphenyldiphenylsulfonium nonafluoro-n-butanesulfonate,-   p-t-butoxyphenyldiphenylsulfonium o-trifluoromethylbenzenesulfonate,-   p-t-butoxyphenyldiphenylsulfonium p-trifluoromethylbenzenesulfonate,-   p-t-butoxyphenyldiphenylsulfonium 10-camphorsulfonate,-   p-t-butoxyphenyldiphenylsulfonium p-toluenesulfonate,-   p-t-butoxyphenyldiphenylsulfonium pyrenesulfonate,-   p-t-butoxyphenyldiphenylsulfonium n-dodecylbenzenesulfonate,-   p-t-butoxyphenyldiphenylsulfonium benzenesulfonate,-   p-t-butoxyphenyldiphenylsulfonium 2,4-difluorobenzenesulfonate,-   p-t-butoxyphenyldiphenylsulfonium n-octanesulfonate,-   p-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    trifluoromethanesulfonate,-   p-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    nonafluoro-n-butanesulfonate,-   p-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    o-trifluoromethylbenzenesulfonate,-   p-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    p-trifluoromethylbenzenesulfonate,-   p-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    10-camphorsulfonate,-   p-t-butoxycarbonylmethoxyphenyldiphenylsulfonium p-toluenesulfonate,-   p-t-butoxycarbonylmethoxyphenyldiphenylsulfonium pyrenesulfonate,-   p-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    n-dodecylbenzenesulfonate,-   p-t-butoxycarbonylmethoxyphenyldiphenylsulfonium benzenesulfonate,-   p-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    2,4-difluorobenzenesulfonate, and-   and p-t-butoxycarbonylmethoxyphenyldiphenylsulfonium    n-octanesulfonate,    (2) Sulfone Compounds

As examples of sulfone compounds, β-ketosulfone, β-sulfonylsulfone, andthe like can be given.

As specific examples of sulfone compounds, phenacylphenylsulfone,mesitylphenacylsulfone, bis(phenylsulfonyl)methane,1,1-bis(phenylsulfonyl)cyclopentane, 1,1-bis(phenylsulfonyl)cyclohexane,4-trisphenacylsulfone, and the like can be given.

(3) Sulfonate Compounds

As examples of sulfonate compounds, alkyl sulfonate, haloalkylsulfonate, aryl sulfonate, imino sulfonate, and the like can be given.

As specific examples of sulfonate compounds, benzointosylate, pyrogalloltristrifluoromethanesulfonate, pyrogallol methanetrisulfonate,nitrobenzyl-9,10-diethoxyanthracene-2-sulfonate,α-methylolbenzointosylate, α-methylolbenzoin n-octanesulfonate,α-methylolbenzoin n-dodecanesulfonate, α-methylolbenzointrifluoromethanesulfonate, and the like can be given.

(4) Sulfonimide Compounds

As examples of sulfonimide compounds, compounds shown by the followingformula (4) can be given:

wherein X represents a divalent group such as an alkylene group, arylenegroup, alkoxylene group, and R²³ represents a monovalent group such asan alkyl group, aryl group, halogenated alkyl group, and halogenatedaryl group.

Specific examples of sulfonimide compounds include:

-   N-(trifluoromethylsulfonyloxy)succinimide,-   N-(trifluoromethylsulfonyloxy)phthalimide,-   N-(trifluoromethylsulfonyloxy)diphenylmaleimide,-   N-(trifluoromethylsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide,-   N-(trifluoromethylsulfonyloxy)-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide,-   N-(trifluoromethylsulfonyloxy)bicyclo[2.2.1]heptan-5,6-oxy-2,3-dicarboxyimide,-   N-(trifluoromethylsulfonyloxy)naphthylimide,-   N-(10-camphorsulfonyloxy)succinimide,-   N-(10-camphorsulfonyloxy)phthalimide,-   N-(10-camphorsulfonyloxy)diphenylmaleimide,-   N-(10-camphorsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide,-   N-(10-camphorsulfonyloxy)-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide,-   N-(10-camphorsulfonyloxy)bicyclo[2.2.1]heptan-5,6-oxy-2,3-dicarboxyimide,-   N-(10-camphorsulfonyloxy)naphthylimide,-   N-(p-methylphenylsulfonyloxy)succinimide,-   N-(p-methylphenylsulfonyloxy)phthalimide,-   N-(p-methylphenylsulfonyloxy)diphenylmaleimide,-   N-(p-methylphenylsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide,-   N-(p-methylphenylsulfonyloxy)-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide,-   N-(p-methylphenylsulfonyloxy)bicyclo[2.2.1]heptane-5,6-oxy-2,3-dicarboxyimide,-   N-(p-methylphenylsulfonyloxy)naphthylimide,-   N-(o-trifluoromethylphenylsulfonyloxy)succinimide,-   N-(o-trifluoroethylphenylsulfonyloxy)phthalimide,-   N-(o-trifluoromethylphenylsulfonyloxy)diphenylmaleimide,-   N-(o-trifluoromethylphenylsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimido,-   N-(o-trifluoromethylphenylsulfonyloxy)-7-oxabicyclo-[2.2.1]hept-5-ene-2,3-dicarboxyimide,-   N-(o-trifluoromethylphenylsulfonyloxy)bicyclo[2.2.1]-heptane-5,    6-oxy-2,3-dicarboxyimide,-   N-(o-trifluoromethylphenylsulfonyloxy)naphthylimide,-   N-(p-fluorophenylsulfonyloxy)succinimide,-   N-(p-fluorophenylsulfonyloxy)phthalimide,-   N-(p-fluorophenylsulfonyloxy)diphenylmaleimide,-   N-(p-fluorophenylsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide,-   N-(p-fluorophenylsulfonyloxy)-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide,-   N-(p-fluorophenylsulfonyloxy)bicyclo[2.2.1]heptane-5,6-oxy-2,3-dicarboxyimide,    and-   N-(p-fluorophenylsulfonyloxy)naphthylimide.    (5) Diazomethane Compounds

As examples of diazomethane compounds, compounds shown by the followingformula (5) can be given:

wherein R²⁴ and R²⁵ individually represent a substituted orunsubstituted, linear, branched, or cyclic alkyl group having 1-20carbon atoms, a substituted or unsubstituted aryl group having 6-20carbon atoms, a substituted or unsubstituted aralkyl group having 7-20carbon atoms, or other monovalent organic groups having a hetero-atomand 1-20 carbon atoms.

Specific examples of diazomethane compounds include:

-   bis(trifluoromethylsulfonyl)diazomethane,-   bis(t-butylsulfonyl)diazomethane,-   bis(cyclohexylsulfonyl)diazomethane,-   bis(phenylsulfonyl)diazomethane,-   bis(p-methylphenylsulfonyl)diazomethane,-   bis(1,4-dioxaspiro[4.5]decane-7-sulfonyl)diazomethane,-   bis(1,5-dioxaspiro[5.5]undecane-8-sulfonyl)diazomethane,-   bis(3,3-dimethyl-1,5-dioxaspiro[5.5]undecane-8-sulfonyl)diazomethane,-   methylsulfonyl.cyclohexylsulfonyldiazomethane,-   methylsulfonyl.phenylsulfonyldiazomethane,-   methylsulfonyl.p-methylphenylsulfonyldiazomethane,-   t-butylsulfonyl.cyclohexylsulfonyldiazomethane,-   t-butylsulfonyl.phenylsulfonyldiazomethane,-   t-butylsulfonyl.p-methylphenylsulfonyldiazomethane,-   cyclohexylsulfonyl.1,4-dioxaspiro[4.5]decane-7-sulfonyldiazomethane,-   cyclohexylsulfonyl.1,5-dioxaspiro[5.5]undecane-8-sulfonyldiazomethane,    and-   cyclohexylsulfonyl.3,3-dimethyl-1,5-dioxaspiro[5.5]undecane-8-sulfonyldiazomethane.    (6) Oxime Sulfonate Compounds

The following compounds can be given as examples of oxime sulfonatecompounds:

-   (5-n-propylsulfonyloxyimino-5H-thiophene-2-indene)-(2-methylphenynone)acetonitrile,-   2,2,2-trifluoro-1-{4-(3-[4-{2,2,2-trifluoro-1-(1-n-propanesulfonyloxyimino)ethyl}phenoxy]n-propoxy)phenyl}ethaneoxime    1-n-propanesulfonate, and the like.

These other acid generators may be used either individually or incombination of two or more.

(B) Resin

The component (B) of the present invention is a resin (hereinafterreferred to as “resin (B)”) having the recurring unit represented by theabove formula (2) (hereinafter referred to as “recurring unit (2)”) andthe recurring unit represented by the above formula (3) (hereinafterreferred to as “recurring unit (3)”).

As examples of a linear, branched, or cyclic alkyl group having 1-6carbon atoms represented by R²² in the formula (2), a methyl group,ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butylgroup, sec-butyl group, t-butyl group, n-pentyl group, neopentyl group,n-hexyl group, cyclopentyl group, cyclohexyl group, and the like can begiven.

Preferable groups for R²² in the formula (2) are a methyl group, ethylgroup, cyclohexyl group, and the like.

A methyl group and an ethyl group are preferable groups for R²¹ in theformula (2).

The group —OCH(R²¹)(OR²²) in the formula (2) forms an acetal structuretogether with the benzene ring in the formula (2), which dissociates inthe presence of an acid.

As specific examples of the recurring unit (2), groups obtained bycleavage of a polymerizable unsaturated bond in the compound such as ap-(1-methoxyethoxy)styrene, p-(1-ethoxyethoxy)styrene,p-(1-n-propoxyethoxy)styrene, p-(1-i-propoxyethoxy)styrene,p-(1-n-butoxyethoxy)styrene, p-(1-t-butoxyethoxy)styrene,p-(1-n-pentyloxyethoxy)styrene, p-(1-neopentyloxyethoxy)styrene,p-(1-n-hexyloxyethoxy)styrene, p-(1-cyclopentyloxyethoxy)styrene,p-(1-cyclohexyloxyethoxy)styrene, p-(1-methoxypropoxy)styrene,p-(1-ethoxypropoxy)styrene, p-(1-n-propoxypropoxy)styrene,p-(1-i-propoxypropoxy)styrene, p-(1-n-butoxypropoxy)styrene,p-(1-t-butoxypropoxy)styrene, p-(1-n-pentyloxypropoxy)styrene,p-(1-neopentyloxypropoxy)styrene, p-(1-n-hexyloxypropoxy)styrene,p-(1-cyclopentyloxypropoxy)styrene, p-(1-cyclohexyloxypropoxy)styrene,or the like can be given.

Of these the recurring units (2), groups obtained by cleavage of apolymerizable unsaturated bond in the compound such as ap-(1-methoxyethoxy)styrene, p-(1-ethoxyethoxy)styrene,p-(1-methoxypropoxy)styrene, p-(1-ethoxypropoxy)styrene,p-(1-cyclohexyloxyethoxy) styrene, or the like are preferable.

The recurring units (2) may be used in the resin (B) either individuallyor in combination of two or more.

The resin (B) may further contain other recurring units and may have astructure partially crosslinked by a suitable cross-linking group (forexample, a cross-linking group having a diethylene glycol skeleton).

Given as examples of such other recurring units are groups obtained bycleavage of a polymerizable unsaturated bond in the following compounds:vinyl aromatic compounds such as styrene, α-methylstyrene,o-methylstyrene, m-methylstyrene, p-methylstyrene, o-methoxystyrene,m-methoxystyrene, p-methoxystyrene, p-t-butoxystyrene,p-t-butoxycarbonyloxystyrene, p-t-butoxycarbonylmethyloxystyrene,p-(2-t-butoxycarbonylethyloxy)styrene, o-hydroxystyrene,m-hydroxystyrene, 3,4-dihydroxystyrene, p-hydroxy-α-methylstyrene,p-acetoxystyrene, p-tetrahydrofuranyloxystyrene, andp-tetrahydropyranyloxystyrene; (meth)acrylatic acid esters such asmethyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate,n-butyl (meth)acrylate, i-butyl (meth)acrylate, sec-butyl(meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate,neopentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl(meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, cyclopentyl (meth)acrylate,1-methylcyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate,1-methylcyclohexyl (meth)acrylate, norbornyl (meth)acrylate, isobornyl(meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentenyl(meth)acrylate, adamantyl (meth)acrylate, 2-adamantyl-2-methyl(meth)acrylate, 2-adamantyl-2-ethyl (meth)acrylate, tetrahydrofuranyl(meth)acrylate, tetrahydropyranyl (meth)acrylate, phenyl (meth)acrylate,benzyl (meth)acrylate, phenethyl (meth)acrylate,(dimethyl)(p-methylcyclohexyl)methyl (meth)acrylate,(dimethyl)(norbornyl)methyl (meth)acrylate, and (dimethyl)(phenyl)methyl(meth)acrylate; unsaturated carboxylic acids such as (meth)acrylic acid,crotonic acid, maleic acid, fumaric acid, and cinnamic acid, as well asanhydrides of these acids; carboxylalkyl esters of unsaturatedcarboxylic acids such as 2-carboxyethyl (meth)acrylate, 2-carboxypropyl(meth)acrylate, and 3-carboxypropyl (meth)acrylate; unsaturated nitrylcompounds such as (meth)acrylonitrile, α-chloroacrylonitrile,crotonitrile, maleinitrile, and fumaronitrile; unsaturated amidecompounds such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide,crotonamide, maleinamide, and fumaramide; unsaturated imide compoundssuch as maleimide, N-phenylmaleimide, and N-cyclohexylmaleimide; andother nitrogen-containing vinyl compounds such as N-vinyl-ε-caprolactam,N-vinylpyrrolidone, 2-vinylpyridine, 3-vinylpyridine, 4-vinylpyridine,2-vinylimidazole, and 4-vinylimidazole.

Of these the recurring units, groups obtained by cleavage of apolymerizable unsaturated bond in the compound such as a styrene,α-methylstyrene, p-t-butoxystyrene, p-t-butoxycarbonyloxystyrene,p-t-butoxycarbonylmethyloxystyrene, p-acetoxystyrene,p-(2-t-butoxycarbonylethyloxy)styrene, t-butyl (meth)acrylate, isobornyl(meth)acrylate, tricyclodecanyl (meth)acrylate, 2-adamantyl-2-methyl(meth)acrylate, 2-adamantyl-2-ethyl (meth)acrylate, or the like arepreferable.

These other recurring units may be used in the resin (B) eitherindividually or in combination of two or more.

The proportion of the recurring units (2) in the total number of therecurring units (2) and the recurring units (3) is preferably 5-90%, andstill more preferably 10-80%, although the proportion varies accordingto the structure of an acetal group in the recurring units (2), typesand amounts of the other recurring units and cross-linking groups, andthe like.

The amount of the other recurring units is usually 50 mol % or less, andpreferably 30 mol % or less.

The amount of the cross-linking groups is usually 15 mol % or less, andpreferably 10 mol % or less of the total recurring units.

The polystyrene-reduced weight average molecular weight (hereinafterreferred to as “Mw”) of the resin (B) determined by gel permeationchromatography is usually 1,000-500,000, and preferably 3,000-300,000.

The ratio of Mw to the polystyrene-reduced number average molecularweight (hereinafter referred to as “Mn”) determined by gel permeationchromatography (Mw/Mn) of the resin (B) is usually 1-5, and preferably1-3.

The resin (B) is prepared using the following methods, for example.

(a) A method of adding a vinyl ether compound such as ethyl vinyl ether,n-butyl vinyl ether, or cyclohexyl vinyl ether to a part of phenolichydroxyl groups in a p-hydroxystyrene (co)polymer under weakly acidicconditions.

(b) A method of adding a vinyl ether compound such as ethyl vinyl ether,n-butyl vinyl ether, or cyclohexyl vinyl ether to a part of phenolichydroxyl groups in p-hydroxystyrene under weakly acidic conditions toproduce a monomer corresponding to the recurring unit (2), andcopolymerizing this monomer with p-hydroxystyrene according to aconventional method.

A partial cross-linked structure in the resin (B) formed by across-linking group having a diethylene glycol skeleton can beintroduced by, for example, reacting an appropriate amount of diethyleneglycol divinyl ether simultaneously in the addition reaction of a vinylether compound in the above method (a).

Other Resins Containing Acid-dissociable Group

In the present invention, acid-dissociable group containing resins otherthan the resin (B) (hereinafter referred to as “other acid-dissociablegroup containing resins”) can be used in combination with the resin (B).Such other acid-dissociable group containing resins will now bedescribed in detail.

Such other acid-dissociable group-containing resins are resins insolubleor scarcely soluble in alkali which are protected by an acid-dissociablegroup and become alkali-soluble when the acid-dissociable groupdissociates.

The term “insoluble or scarcely soluble in alkali” used herein refers tocharacteristics in which 50% or more of the initial thickness of a resinfilm remains after development under alkaline development conditionsemployed when forming a resist pattern using a resist film formed fromthe radiation-sensitive resin composition comprising otheracid-dissociable group containing resins.

As examples of other acid-dissociable group-containing resins, a resininsoluble or scarcely soluble in alkali by itself, which has a structurein which a hydrogen atom of an acidic functional group in analkali-soluble resin having one or more acidic functional groups such asa phenolic hydroxyl group and a carboxyl group (for example, analkali-soluble resin having one or more recurring units shown by thefollowing formulas (6) to (8)) is replaced by one or moreacid-dissociable groups which dissociate in the presence of an acid(hereinafter called “resin (b1)”), and a resin insoluble or scarcelysoluble in alkali by itself, which has a structure in which a hydrogenatom of a phenolic hydroxyl group in an alkali-soluble resin having oneor more recurring units shown by the following formula (9) is replacedby one or more acid-dissociable groups which dissociate in the presenceof an acid (hereinafter called “resin (b2)”) can be given, (the resin(b1) and resin (b2) are hereinafter collectively referred to as “resin(b)”)

wherein R²⁶ represents a hydrogen atom or a methyl group, R²⁷ is ahalogen atom or an organic group having 1-6 carbon atoms, and n is aninteger of 0-3;

wherein R²⁸ represents a hydrogen atom or a methyl group;

wherein R²⁹, R³⁰, R³¹, R³², and R³³ individually represent a hydrogenatom or a linear or branched alkyl group having 1-4 carbon atoms.

As examples of the acid-dissociable group in the resin (b), asubstituted methyl group, 1-substituted ethyl group, 1-substitutedpropyl group, 1-branched alkyl group, silyl group, germyl group,alkoxycarbonyl group, acyl group, cyclic acid-dissociable group, and thelike can be given. When a structure obtained by replacing a hydrogenatom of a phenolic hydroxyl group in the unit originating fromp-hydroxystyrene by an acid-dissociable group corresponds to therecurring unit (2), such an acid-dissociable group is excluded from theacid-dissociable group in the resin (b).

As examples of a substituted methyl group, a methoxymethyl group,methylthiomethyl group, ethoxymethyl group, ethylthiomethyl group,methoxyethoxymethyl group, benzyloxymethyl group, benzylthiomethylgroup, phenacyl group, bromophenacyl group, methoxyphenacyl group,methylthiophenacyl group, α-methylphenacyl group, cyclopropylmethylgroup, benzyl group, diphenylmethyl group, triphenylmethyl group,bromobenzyl group, nitrobenzyl group, methoxybenzyl group,methylthiobenzyl group, ethoxybenzyl group, ethylthiobenzyl group,piperonyl group, methoxycarbonylmethyl group, ethoxycarbonylmethylgroup, n-propoxycarbonylmethyl group, i-propoxycarbonylmethyl group,n-butoxycarbonylmethyl group, t-butoxycarbonylmethyl group, and the likecan be given.

As examples of the 1-substituted ethyl group, a 1-methoxyethyl group,1-methylthioethyl group, 1,1-dimethoxyethyl group, 1-ethoxyethyl group,1-ethylthioethyl group, 1,1-diethoxyethyl group, 1-phenoxyethyl group,1-phenylthioethyl group, 1,1-diphenoxyethyl group, 1-benzyloxyethylgroup, 1-benzylthioethyl group, 1-cyclopropylethyl group, 1-phenylethylgroup, 1,1-diphenylethyl group, 1-methoxycarbonylethyl group,1-ethoxycarbonylethyl group, 1-n-propoxycarbonylethyl group,1-i-propoxycarbonylethyl group, 1-n-butoxycarbonylethyl group,1-t-butoxycarbonylethyl group, and the like can be given.

As examples of 1-branched alkyl group, an i-propyl group, sec-butylgroup, t-butyl group, 1,1-dimethylpropyl group, 1-methylbutyl group,1,1-dimethylbutyl group, and the like can be given.

As examples of a 1-substituted propyl group, a 1-methoxypropyl group,1-ethoxypropyl group, and the like can be given.

As examples of the silyl group, a trimethylsilyl group,ethyldimethylsilyl group, methyldiethylsilyl group, triethylsilyl group,i-propyldimethylsilyl group, methyldi-i-propylsilyl group,tri-i-propylsilyl group, t-butyldimethylsilyl group,methyldi-t-butylsilyl group, tri-t-butylsilyl group, phenyldimethylsilylgroup, methyldiphenylsilyl group, triphenylsilyl group, and the like canbe given.

As examples of the germyl group, a trimethylgermyl group,ethyldimethylgermyl group, methyldiethylgermyl group, triethylgermylgroup, i-propyldimethylgermyl group, methyldi-i-propylgermyl group,tri-i-propylgermyl group, t-butyldimethylgermyl group,methyldi-t-butylgermyl group, tri-t-butylgermyl group,phenyldimethylgermyl group, methyldiphenylgermyl group, triphenylgermylgroup, and the like can be given.

As examples of the alkoxycarbonyl group, a methoxycarbonyl group,ethoxycarbonyl group, i-propoxycarbonyl group, t-butoxycarbonyl group,and the like can be given.

As examples of the acyl group, an acetyl group, propionyl group, butyrylgroup, heptanoyl group, hexanoyl group, valeryl group, pivaloyl group,isovaleryl group, lauryloyl group, myristoyl group, palmitoyl group,stearoyl group, oxalyl group, malonyl group, scucinyl group, glutarylgroup, adipoyl group, piperoyl group, suberoyl group, azelaoyl group,sebacoyl group, acryloyl group, propioloyl group, methacryloyl group,crotonoyl group, oleoyl group, maleoyl group, fumaroyl group, mesaconoylgroup, campholoyl group, benzoyl group, phthaloyl group, isophthaloylgroup, terephthaloyl group, naphthoyl group, toluoyl group,hydroatropoyl group, atropoyl group, cinnamoyl group, furoyl group,thenoyl group, nicotinoyl group, isonicotinoyl group, p-toluenesulfonylgroup, mesyl group, and the like can be given.

As examples of the cyclic acid-dissociable group, a cyclopropyl group,cyclopentyl group, cyclohexyl group, cyclohexenyl group,p-methoxycyclohexyl group, tetrahydropyranyl group, tetrahydrofuranylgroup, tetrahydrothiopyranyl group, tetrahydrothiofuranyl group,3-bromotetrahydropyranyl group, 4-methoxytetrahydropyranyl group,4-methoxytetrahydrothiopyranyl group, 3-tetrahydrothiophene-1,1-dioxidegroup, and the like can be given.

Of these acid-dissociable groups, a t-butyl group, 1-methoxymethylgroup, 1-methoxyethyl group, 1-ethoxyethyl group, 1-ethoxypropyl group,1-propoxyethyl group, trimethylsilyl group, t-butoxycarbonyl group,t-butoxycarbonylmethyl group, tetrahydropyranyl group, tetrahydrofuranylgroup, and the like are preferable.

The percentage of the acid-dissociable group introduced into the resin(b) (percentage of the number of acid-dissociable groups among the totalnumber of acidic functional groups and acid-dissociable groups in theresin (b)) is preferably 10-100%, and still more preferably 15-100%,although the percentage varies depending on types of acid-dissociablegroup and the alkali-soluble resin into which the acid-dissociable groupis introduced.

Mw of the resin (b) is preferably 1,000-150,000, and still morepreferably 3,000-100,000.

Mw/Mn of the resin (b) is 1-5, and preferably 1-3. The resin (b) isprepared using a method of introducing one or more acid-dissociablegroups into an alkali-soluble resin prepared in advance, the resin (b1)is prepared by (co)polymerizing one or more polymerizable unsaturatedmonomers having an acid-dissociable group, and the resin (b2) isprepared by (co)polycondensing one or more polycondensing componentshaving an acid-dissociable group.

In the present invention, the above other acid-dissociablegroup-containing resins can be used either individually or incombination of two or more.

Other Additives

The radiation-sensitive resin composition of the present inventioncontains the acid generator (A) and the resin (B) as essentialcomponents, and may further contain other acid generators and otheracid-dissociable group-containing resins as optional components. Inaddition to these components, additives such as dissolution controllers,acid diffusion controllers, surfactants, and sensitizers may be added tothe radiation-sensitive resin composition of the present invention.

Dissolution Controller

As a dissolution controller, a compound having an acid functional groupsuch as a phenolic hydroxyl group, carboxyl group, or the like, acompound obtained by replacing one or more hydrogen atoms in such acompound by a substitution group capable of dissociating in the presenceof an acid (hereinafter referred to as “acid-dissociable substituent”),and the like can be given.

As examples of such an acid-dissociable substituent, the same groups asthe acid-dissociable group mentioned in connection with the otheracid-dissociable group-containing resins, such as a substituted methylgroup, 1-substituted ethyl group, 1-substituted n-propyl group,1-branched alkyl group, silyl group, germyl group, alkoxycarbonyl group,acyl group, cyclic acid-dissociable group, and the like, can be given.

The alkali solubility control agent may be either a low molecular weightcompound or a high molecular weight compound. The compounds shown by thefollowing formulas (10) to (14) can be given as specific examples of thelow molecular weight compound.

wherein R³⁴ groups individually indicate a hydrogen atom or anacid-dissociable substituent, R³⁵ groups individually represent a linearor branched alkyl group having 1-4 carbon atoms, a phenyl group, or a1-naphthyl group, p is an integer of 1 or more, and q is an integer of 0or more, provided that p+q≦6;

wherein R³⁴ and R³⁵ are the same as defined for the above formula (10),and A represents —O—, —S—, —CO—, —COO—, —SO—, —SO₂—, —C(R³⁶)(R³⁷)—,wherein R³⁶ and R³⁷ individually represent a hydrogen atom, a linear,branched, or cyclic alkyl group having 1-6 carbon atoms, an acyl grouphaving 2-11 carbon atoms, a phenyl group, or a 1-naphthyl group, or agroup shown by the following formula,

wherein R³⁵ is the same as defined above and x is an integer of 0-4, andp, q, r, and s are integers of 0 or more, provided that p+q≦5, r+s≦5,and p+r≧1 are satisfied;

wherein R³⁴ and R³⁵ are the same as those defined in the formula (10),R³⁸ represents a hydrogen atom, a linear or branched alkyl group having1-4 carbon atoms, or a phenyl group, and p, q, r, s, t, and u areintegers of 0 or more, provided that p+q≦5, r+s≦5, t+u≦5, and p+r+t≧1are satisfied;

wherein R³⁴ and R³⁵ are the same as defined for the above formula (10),A is the same as defined in the above formula (11), R³⁸ is the same asdefined in the formula (12), provided that when two or more R³⁸ groupsare present, such groups may be either identical or different, and p, q,r, s, t, u, v, and w are integers of 0 or more, provided that p+q≦5,r+s≦5, t+u≦5, v+w≦5, and p+r+t+v≧1 are satisfied; and

wherein R³⁴ and R³⁵ are the same as defined for the above formula (10),R³⁸ is the same as defined in the formula (12), provided that when twoor more R³⁸ groups are present, such groups may be either identical ordifferent, and p, q, r, s, t, u, v, and w are integers of 0 or more,provided that p+q≦5, r+s≦5, t+u≦5, v+w≦4, and p+r+t+v≧1 are satisfied.

These dissolution controllers may be used either individually or incombination of two or more.

Acid Diffusion Controller

The acid diffusion controller controls diffusion of an acid generatedfrom the acid generator (A) upon exposure in the resist film andsuppresses undesired chemical reactions in the unexposed area. Theaddition of the acid diffusion controller improves storage stability ofthe composition and resolution as a resist. Moreover, the addition ofthe acid diffusion controller prevents the line width of the resistpattern from changing due to variation of post-exposure delay (PED) fromexposure to development, whereby a composition with remarkably superiorprocess stability can be obtained.

As examples of such acid diffusion controllers, a compound shown by thefollowing formula (15) (hereinafter called “nitrogen-containing compound(i)”),

wherein R³⁹, R⁴⁰, and R⁴¹ individually represents a hydrogen atom, asubstituted or unsubstituted alkyl group, substituted or unsubstitutedaryl group, or substituted or unsubstituted aralkyl group; a diaminocompound having two nitrogen atoms in the molecule (hereinafter referredto as “nitrogen-containing compound (ii)”); a polymer having three ormore nitrogen atoms in the molecule (hereinafter referred to as“nitrogen-containing compound (iii)”); a low molecular weight compoundwith one or more amino groups having at least one hydrogen atom bondedto the nitrogen atom, in which one or more hydrogen atoms are replacedby a t-butoxycarbonyl group (hereinafter referred to as“nitrogen-containing compound (iv)”); an amide group-containingcompound, urea compound, nitrogen-containing heterocyclic compound; andthe like can be given.

The following compounds can be given as examples of thenitrogen-containing compound (i): linear, branched, or cyclicmonoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine,n-nonyamine, n-decylamine, n-dodecylamine, and cyclohexylamine; linear,branched, or cyclic dialkylamines such as di-n-butylamine,di-n-pentylamine, di-n-hexylamine, di-n-heptylamine, di-n-octylamine,di-n-nonylamine, di-n-decylamine, methyl.n-dodecylamine,di-n-dodecylamine, methyl-cyclohexylamine, and dicyclohexylamine;linear, branched, or cyclic trialkylamines such as triethylamine,tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine,tri-n-hexylamine, tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine,tri-n-decylamine, n-dodecyldimethylamine, methyl di-n-dodecyl amine,tri-n-dodecylamine, cyclohexyldimethylamine, methyldicyclohexylamine,and tricyclohexylamine; linear, branched, or cyclic alkanolamines suchas ethanolamine, diethanolamine, triethanolamine, andtri-i-propanolamine, and aromatic amines such as aniline,N-methylaniline, N,N-dimethylaniline, o-methylaniline, m-methylaniline,p-methylaniline, p-nitroaniline, methyl-phenylamine, diphenylamine,phenyldimethylamine, methyldiphenylamine, triphenylamine,1-naphthylamine, and 2-naphthylamine.

Examples of the nitrogen-containing compounds (ii) includeethylenediamine, N,N,N′,N′-tetramethylenediamine, tetramethylenediamine,hexamethylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diamino diphenylether, 4,4′-diaminobenzophenone, 4,4′-diaminodiphenylamine,N,N,N′,N′-tetrakis(2-hydroxyethyl)ethylenediamine,N,N,N′,N′-tetrakis(2-hydroxypropyl)ethylenediamine,2,2-bis(p-aminophenyl)propane,2-(m-aminophenyl)-2-(p-aminophenyl)propane,2-(p-aminophenyl)-2-(m-hydroxyphenyl)propane,2-(p-aminophenyl)-2-(p-hydroxyphenyl)propane,1,4-bis[1-(p-aminophenyl)-1-methylethyl]benzene,1,3-bis[1-(p-aminophenyl)-1-methylethyl]benzene, bis(2-dimethylaminoethyl)ether, bis(2-diethylaminoethyl)ether, and thelike. As examples of the nitrogen-containing compound (iii),polyethyleneimine, polyallylamine, a polymer ofdimethylaminoethylacrylamide, and the like can be given.

The following compounds can be given as examples of thenitrogen-containing compound (iv): linear, branched, or cyclicdialkylamines such as N-t-butoxycarbonyl di-n-octylamine andN-t-butoxycarbonyldicyclohexylamine; adamantylamine derivatives such asN-t-butoxycarbonyl-1-adamantylamine,N-t-butoxycarbonyl-N-methyl-1-adamantylamine, andN,N-di-t-butoxycarbonyl-1-adamantylamine; other diamine derivatives suchas N-t-butoxycarbonyl-4,4′-diaminodiphenylmethane,N,N′-di-t-butoxycarbonyl-4,4′-diaminodiphenylmethane,N,N′-di-t-butoxycarbonylhexamethylenediamine,N,N,N′N′-tetra-t-butoxycarbonylhexamethylenediamine,N,N′-di-t-butoxycarbonyl-1,7-diamino-n-heptane,N,N′-di-t-butoxycarbonyl-1,8-diamino-n-octane,N,N′-di-t-butoxycarbonyl-1,10-diamino-n-decane, andN,N′-di-t-butoxycarbonyl-1,12-diamino-n-dodecane; and imidazolederivatives such as N-t-butoxycarbonylbenzimidazole,N-t-butoxycarbonyl-2-methylbenzimidazole, andN-t-butoxycarbonyl-2-phenylbenzimidazole.

Examples of compounds containing an amide group include formamide,N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide,N,N-dimethylacetamide, propionamide, benzamide, pyrrolidone,N-methylpyrrolidone, and the like.

Examples of the urea compounds include urea, methylurea,1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea,1,3-diphenylurea, tri-n-butylthiourea, and the like.

Examples of the nitrogen-containing heterocyclic compounds includeimidazoles such as imidazole, 4-methylimidazole, 2-phenylimidazole,4-methyl-2-phenylimidazole, benzimidazole, and 2-phenylbenzimidazole;pyridines such as pyridine, 2-methylpyridine, 4-methylpyridine,2-ethylpyridine, 4-ethylpyridine, 2-phenylpyridine, 4-phenylpyridine,2-methyl-4-phenylpyridine, 2-benzylpyridine, 4-benzylpyridine,2,6-dimethanolpyridine, nicotine, nicotinic acid, nicotinic acid amide,quinoline, 8-oxyquinoline, and acridine; pyrazine, pyrazole, pyridazine,quinoxaline, purine, pyrrolidine, piperidine, piperidine ethanol,morpholine, 4-methylmorpholine, piperazine, 1,4-dimethylpiperazine,1,4-diazabicyclo[2.2.2]octane; and the like.

Of these nitrogen-containing organic compounds, nitrogen-containingcompounds (i), nitrogen-containing compounds (iv), andnitrogen-containing heterocyclic compounds are preferable. Among thenitrogen-containing compounds (i), trialkylamines and alkanolamines areparticularly preferable. Among the nitrogen-containing compounds (iv),dialkylamine derivatives and imidazole derivatives are particularlypreferable. Among the nitrogen-containing heterocyclic compounds,imidazoles and pyridines are particularly preferable.

The acid diffusion controller may be used either individually or incombination of two or more.

Surfactant:

Surfactants improve applicability, striation, and developability of theradiation-sensitive resin composition.

As surfactants, any of anionic-type surfactants, cationic-typesurfactants, nonionic-type surfactants, and ampholytic-type surfactantsmay be used. Of these, nonionic-type surfactants are preferable.

As examples of nonionic-type surfactants, polyoxyethylene higher alkylethers, polyoxyethylene higher alkyl phenyl ethers, higher fatty aciddiesters of polyethylene glycol, commercially available products such asKP (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow(manufactured by Kyoeisha Chemical Co., Ltd.), EFTOP (manufactured byTOHKEM PRODUCTS CORPORATION), MEGAFAC (manufactured by Dainippon Ink andChemicals, Inc.), Fluorad (manufactured by Sumitomo 3M, Ltd.), AsahiGuard, Surflon (manufactured by Asahi Glass Co., Ltd.), and the like canbe given.

These surfactants may be used either individually or in combination oftwo or more.

Sensitizers Etc.

Sensitizers absorb energy of radiation and transmit the energy to theacid generator (A) or other acid generators, thereby increasing theamount of an acid to be generated upon exposure. The sensitizers thusimprove apparent sensitivity of the radiation-sensitive resincomposition.

As examples of preferable sensitizers, acetophenones, benzophenones,naphthalenes, biacetyl, Eosine, Rose Bengale, pyrenes, anthracenes,phenothiazines, and the like can be given.

These sensitizers may be used either individually or in combinations oftwo or more. The addition of dyes or pigments visualizes a latent imagein the exposed area, thereby relaxing the effect of halation at the timeof exposure. Use of adhesion improvers improves adhesion to substrates.

As other additives, halation inhibitors, preservation stabilizers,antifoaming agents, form improvers, and the like can be added. Specificadditives include 4-hydroxy-4′-methylchalcone, and the like.

Radiation-sensitive Resin Composition

The radiation-sensitive resin composition of the present inventioncontains the acid generator (A) and the resin (B) as essentialcomponents, and may further contain other acid generators, otheracid-dissociable group-containing resins, and other additives. Theproportion of major components in the radiation-sensitive resincomposition is as follows.

The amount of the acid generator (A) is usually 0.01-20 parts by weight,preferably 0.1-15 parts by weight, and still more preferably 0.3-8 partsby weight for 100 parts by weight of the total amount of resincomponents in the resin composition. If the amount of acid generator (A)is less than 0.01 part by weight, sensitivity and resolution as a resistand the effect of decreasing nano-edge roughness tend to be impaired; ifmore than 20 parts by weight, coatablity and heat resistance as a resisttends to decrease.

The amount of the acid generator (A) and other acid generators isusually 0.02-80 parts by weight, preferably 0.2-50 parts by weight, andstill more preferably 0.3-30 parts by weight for 100 parts by weight ofthe total amount of resin components in the resin composition.

The amount of the acid generator (A) among the total amount of acidgenerators is preferably 0.5 wt % or more, and particularly preferably 1wt % or more. If the amount of the acid generator (A) is less than 0.5wt %, the effect of decreasing nano-edge roughness may be impaired.

The amount of the resin (B) used in the whole acid-dissociablegroup-containing resins is usually 10 wt % or more, and preferably 20 wt% or more. If the amount of the resin (B) is less than 10 wt %,resolution as a resist tends to be impaired.

The amount of dissolution controllers is 50 parts by weight or less, andpreferably 30 parts by weight or less, for 100 parts by weight of thetotal amount of resin components, although the specific amount variesaccording to the types of the dissolution controllers, resin (B), andresin (b). If the amount of the dissolution controllers exceeds 50 partsby weight, heat resistance as a resist tends to decrease.

The amount of acid diffusion controllers is usually 10 parts by weightor less, and preferably 5 parts by weight or less, for 100 parts byweight of the total amount of resin components, although the specificamount varies according to the types of the acid diffusion controllers,acid generator (A), and other acid generators. If the amount of the aciddiffusion controllers is more than 10 parts by weight, sensitivity as aresist and developability of the exposed area tend to decrease.

The proportion of the surfactants to be added is usually 2 parts byweight or less, as an effective component of the surfactants, for 100parts by weight of the total resin component in the resin composition.

The amount of sensitizers to be added is 50 parts by weight or less, andpreferably 30 parts by weight or less, for 100 parts by weight of thetotal amount of resins in the resin composition.

Composition Solution

The radiation-sensitive resin composition of the present invention isprepared as a composition solution by dissolving the components in asolvent so that the solid content is usually in the range of 1-50 wt %and filtering the composition using a filter with a pore diameter ofabout 0.2 μm.

As the solvents, ethers, esters, ether esters, ketones, ketone esters,amides, amide esters, lactams, lactones, and (halogenated) hydrocarbonsare used. Specific examples include ethylene glycol monoalkyl ethers,diethylene glycol dialkyl ethers, propylene glycol monoalkyl ethers,propylene glycol dialkyl ethers, ethylene glycol monoalkyl etheracetates, propylene glycol monoalkyl ether acetates, acetic acid esters,hydroxyacetates, lactates, alkoxyacetate, acetoacetate, pyruvates,propionates, butyrates, 2-hydroxy-2-methyl propionate,3-alkoxypropionate, 2-hydroxy-3-methyl butyrate, cyclic or non-cyclicketones, N,N-dialkylformamides, N,N-dialkylacetamides,N-alkylpyrrolidones, γ-lactones, (halogenated) aliphatic hydrocarbons,(halogenated) aromatic hydrocarbons, and the like.

Examples of specific compounds used as a solvent include ethylene glycolmonomethyl ether, ethylene glycol monoethyl ether, ethylene glycolmono-n-propyl ether, ethylene glycol mono-n-butyl ether, diethyleneglycol dimethyl ether, diethylene glycol diethyl ether, diethyleneglycol di-n-propyl ether, diethylene glycol di-n-butyl ether, ethyleneglycol monomethyl ether acetate, ethylene glycol monoethyl etheracetate, propylene glycol monomethyl ether acetate, propylene glycolmonoethyl ether acetate, propylene glycol mono-n-propyl ether acetate,iso-propenyl propionate, ethyl acetate, n-propyl acetate, isopropenylacetate, n-butyl acetate, 3-methoxybutyl acetate, ethyl lactate,3-methyl-3-methoxybutyl acetate, hydroxyethyl acetate, ethoxyethylacetate, methyl acetoacetate, ethyl acetoacetate, isopropenylpropionate, 3-methyl-3-methoxybutyl propionate, ethyl 2-hydroxy-2-methylpropionate, methyl 3-methoxy propionate, ethyl 3-methoxy propionate,3-ethoxymethyl propionate, 3-ethoxyethyl propionate, methyl2-hydroxy-3-methyl butyrate, methyl ethyl ketone, cyclohexanone,2-heptanone, 3-heptanone, 4-heptanone, N,N-dimethylformamide,N,N-dimethylacetamide, N-methylpyrrolidone, toluene, xylene, and thelike.

Of these solvents, propylene glycol monoalkyl ether acetates, lactates,3-alkoxypropionates, 2-heptanone, cycloheptanone, and the like arepreferable.

These solvents may be used either individually or in combination of twoor more.

One or more solvents with a high boiling point may be added to thesolvent. Examples of such solvents with a high boiling point includebenzyl ethyl ether, di-n-hexyl ether, diethylene glycol monomethylether, diethylene glycol monoethyl ether, acetonylacetone, isophorone,caproic acid, caprylic acid, 1-octanol, 1-nonanol, benzyl alcohol,benzyl acetate, ethyl benzoate, diethyl oxalate, diethyl maleate,γ-butyrolactone, ethylene carbonate, propylene carbonate, ethyleneglycol monophenyl ether acetate, and the like.

Formation of Resist Pattern

The radiation-sensitive resin composition of the present inventioncontains the resin (B) having an acid-dissociable acetal structure. Theacetal structure dissociates by the action of an acid generated from theacid generator (A) or the like by radiation and forms a phenolichydroxyl group which renders the resin soluble or easily soluble inalkali, whereby a positive-tone resist pattern can be formed.

To form a resist pattern from the radiation-sensitive resin compositionof the present invention, the composition solution prepared as mentionedabove is applied to a substrate by a method such as rotational coating,cast coating, or roll coating to form a resist film.

As a substrate, a silicon substrate, a substrate covered with aluminum,a basic substrate of silicon nitride or titanium nitride, a substratecovered with an inorganic nitride film or an organic antireflectionfilm, and the like can be used.

After a heat treatment or pre-baking (hereinafter referred to as “PB”),the resist film is exposed to radiation through a mask with a prescribedpattern. As examples of radiation which can be used here, deepultraviolet rays such as a bright line spectrum of a mercury lamp(wavelength: 254 nm), KrF excimer laser (wavelength: 248 nm), ArFexcimer laser (wavelength: 193 nm), and F2 excimer laser (wavelength:157 nm), as well as charged particle rays such as electron beams arepreferable. Moreover, according to the types of other acid generators,X-rays such as synchrotron radiation, and ultraviolet rays such asi-rays (wavelength: 365 nm) can be used. The exposure conditions such asthe amount of rays are determined appropriately according to thecomposition of the resin composition, types of other additives, and thelike.

After exposure, a post exposure bake (hereinafter referred to as “PEB”)is preferably performed in order to improve the apparent sensitivity ofthe resist. The heating temperature is usually 30-200° C., andpreferably 50-150° C., although the heating conditions vary according tothe composition of the resin composition, types of other additives, andthe like.

The resist coating is then developed using an alkaline developer to forma specific resist pattern.

As the above alkaline developer, an alkaline aqueous solution containingone or more alkaline compounds such as alkaline metal hydroxides,aqueous ammonia, alkylamines, alkanolamines, heterocyclic amines,tetraalkylammonium hydroxides, corrin,1,8-diazabicyclo[5.4.0]-7-undecene, and 1,5-diazabicyclo[4.3.0]-5-noneneat a concentration of usually 5-10 wt %, and preferably 2-5 wt % isused. Of these, an aqueous solution of tetraalkylammonium hydroxides isparticularly preferable.

An appropriate amount of a water-soluble organic solvent such asmethanol and ethanol, surfactants, and the like may be added to adeveloper consisting of an alkaline aqueous solution.

When a developer consisting of the above alkaline aqueous solution isused, the resist film is generally washed after development.

EXAMPLES

The embodiments of the present invention will be described in moredetail by examples. However, these examples should not be construed aslimiting the present invention.

Examples 1-14 and Comparative Examples 1-2

Components shown in Table 1 (part(s) indicates part(s) by weight) weremixed to prepare homogeneous solutions. The solutions were filteredthrough a Teflon membrane filter with a pore diameter of 0.2 μm toprepare solution compositions.

The composition solutions were coated on a silicon wafer by rotationcoating and pre-baked at the temperature and period of time shown inTable 2 to form resist films with a thickness of 0.5 μm or 0.1 μm (inthe case where the film is exposed to an F2 excimer laser). The resistfilms were exposed to a KrF excimer laser with a wavelength of 248 nmusing a KrF excimer laser irradiation apparatus “NSR-2005 EX8A”(manufactured by Nikon Corp.) through a mask pattern while changing thedose of radiation. In some of the Examples, instead of a KrF excimerlaser, the resist films were exposed to electron beams using asimple-type electron beam direct patterning apparatus (50 KeV)(“HL700D-M” (current density 4.5 A) manufactured by Hitachi, Ltd.) or asimple-type F2 excimer laser irradiation apparatus (manufactured byExitech Co.) through a mask pattern while changing the dose ofradiation. After exposure to radiation, the resist films were treatedwith heat (PEB) at the temperature and period of time shown in Table 2.The resist films were then developed in a 2.38 wt % tetramethyl ammoniumhydroxide aqueous solution at 23° C. for 60 seconds, washed with waterfor 30 seconds, and dried to form resist patterns.

The evaluation results of the Examples and Comparative Examples areshown in Table 3. The results of sensitivity and resolution are shownfor samples exposed to an F2 excimer laser because the resist films usedwere too thin to obtain the results of nano-edge roughness evaluation.

Evaluation of resists was carried out as follows.

Sensitivity

Sensitivity was evaluated based on an optimum exposure dose which is adose capable of forming a 1:1 line and space pattern (1L1S) with a linewidth of 0.25 μm, when a resist film formed on a silicon wafer isexposed to light at a varied dose, immediately followed by baking,alkali development, washing with water, and drying.

Resolution

The minimum dimension (μm) of a resist pattern resolved at the optimumdose was taken as the resolution of the resist film.

Nano-edge Roughness

A 1L1S line pattern with a designed line width of 0.25 μm was observedby a scanning electron microscope to measure a dimension (ΔCD), which isa maximum projection from the designed line width of 0.25 μm in theirregularity produced along the side of the line pattern, as shown inFIG. 1. The nano-edge roughness of resist films was evaluated accordingto the following standard. FIG. 1(a) is a plan view and FIG. 1(b) is aside view of a resist pattern. The irregularity shown in the FIGURE isexaggerated for explanation.

-   -   ΔCD<0.01 μm: Good    -   ΔCD≧0.01 μm: Bad

The following components were used in Examples and Comparative Examples.

Acid Generator (A)

-   A-1: 2,4,6-trimethylphenyldiphenylsulfonium    2,4-difluorobenzenesulfonate-   A-2: 2,4,6-trimethylphenyldiphenylsulfonium    4-trifluoromethylbenzenesulfonate-   A-3: 4-t-butoxy-2,6-dimethylphenyldiphenylsulfonium    2,3,4,5,6-pentafluorobenzenesulfonate-   A-4: 4-t-butoxycarbonylmethoxy-2,6-dimethylphenyldiphenylsulfonium    2,4,6-tris(trifluoromethyl)benzenesulfonate-   a-1: 1,1-bis(phenylsulfonyl)cyclohexane-   a-2: triphenylsulfonium nonafluoro-n-butanesulfonate-   a-3: bis(4-t-butylphenyl)iodonium 10-camphorsulfonate-   a-4: bis(cyclohexylsulfonyl)diazomethane-   a-5: bis(1,4-dioxaspiro[4.5]decane-7-sulfonyl)diazomethane-   a-6: bis(t-butylsulfonyl)diazomethane-   a-7:    (5-propylsulfoniumoxyimino-5H-thiophen-2-ilydene)-(2-methylphenyl)acetonitrile,    (B) Resin-   B-1: poly(p-hydroxystyrene) resin in which 34 mol % of hydrogen    atoms of phenolic hydroxyl groups have been replaced by    1-ethoxyethyl groups (Mw=9,000, Mw/Mn=1.9)-   B-2: poly(p-hydroxystyrene) resin in which 15 mol % of hydrogen    atoms of phenolic hydroxyl groups have been replaced by    1-ethoxyethyl groups and 18 mol % by 1-ethoxypropyl groups    (Mw=10,000, Mw/Mn=1.2)-   B-3: poly(p-hydroxystyrene) resin in which 25 mol % of hydrogen    atoms of phenolic hydroxyl groups have been replaced by    1-ethoxyethyl groups and 8 mol % by t-butoxycarbonyl groups    (Mw=10,000, Mw/Mn=1.1)-   B-4: poly(p-hydroxystyrene) resin in which 23 mol % of hydrogen    atoms of phenolic hydroxyl groups have been replaced by    1-ethoxyethyl groups and 10 mol % by t-butyl groups (Mw=12,000,    Mw/Mn=1.2)-   B-5: p-hydroxystyrene/styrene copolymer (copolymerization ratio:    90:10) resin in which 25 mol % of hydrogen atoms of phenolic    hydroxyl groups have been replaced by 1-cyclohexyloxyethyl groups    (Mw=18,000, Mw/Mn=1.9)-   B-6: p-hydroxystyrene/t-butyl acrylate copolymer (copolymerization    ratio: 90:10) resin in which 25 mol % of hydrogen atoms of phenolic    hydroxyl groups have been replaced by 1-ethoxyethyl groups    (Mw=18,000, Mw/Mn=1.8)-   B-7: Partially cross-linked resin (a hexamer in average) prepared by    cross-linking poly(p-hydroxystyrene) (Mw=5,000, Mw/Mn=1.8), in which    24 mol % of hydrogen atoms of phenolic hydroxyl groups have been    replaced by 1-ethoxyethyl groups, using a cross-linker having a    diethylene glycol skeleton (Mw=30,000, Mw/Mn=5.0) The cross-linking    reaction was carried out by reacting the poly(p-hydroxystyrene)    (Mw=5,000) with ethyl vinyl ether and diethylene glycol divinyl    ether in the presence of pyridinium p-toluenesulfonate.    Resin (b)-   b-1: poly(p-hydroxystyrene) resin in which 26 mol % of hydrogen    atoms of phenolic hydroxyl groups have been replaced by    t-butoxycarbonyl groups (Mw=9,000, Mw/Mn=1.9)-   b-2: poly(p-hydroxystyrene) resin in which 25 mol % of hydrogen    atoms of phenolic hydroxyl groups have been replaced by    t-butoxycarbonylmethyl groups (Mw=25,000, Mw/Mn=1.2)-   b-3: poly(p-hydroxystyrene) resin in which 32 mol % of hydrogen    atoms of phenolic hydroxyl groups have been replaced by t-butyl    groups (Mw=15,000, Mw/Mn=1.1)-   b-4: p-hydroxystyrene/styrene/butyl acrylate copolymer    (copolymerization ratio: 60:20:20, Mw=12,500, Mw/Mn=1.8)    Dissolution Controller-   C-1: diphenolic acid-   C-2: 2-hydroxybenzophenone    Acid Diffusion Controller-   D-1: n-dodecyldimethylamine-   D-2: tri-n-hexylamine-   D-3: benzimidazole-   D-4: 2-benzylpyridine-   D-5: 2-phenylbenzimidazole-   D-6: triethanolamine-   D-7: tri-n-octylamine    Solvent-   E-1: ethyl lactate-   E-2: propylene glycol monomethyl ether acetate-   E-3: 2-heptanone

TABLE 1 Acid generator Dissolution Acid diffusion A a Resin controllercontroller Solvent Example 1 A-2 (1) a-4 (6) B-1 (100) — D-1 (0.70) E-2(800) Example 2 A-1 (0.8) a-5 (8) B-1 (50) — D-2 (0.30) E-1 (240) b-1(50) D-5 (0.15) E-2 (560) Example 3 A-4 (1.5) a-1 (1) B-2 (80) — D-4(0.35) E-3 (800) a-4 (6) b-2 (20) Example 4 A-1 (2) a-2 (0.5) B-3 (100)C-1 (5) D-5 (0.20) E-1 (240) a-5 (5) D-6 (0.15) E-2 (560) Example 5 A-3(1.5) a-1 (1.5) B-2 (100) — D-3 (0.70) E-2 (800) a-6 (4.5) Example 6 A-2(3.5) — B-7 (100) — D-6 (0.20) E-1 (240) D-7 (0.30) E-2 (560) Example 7A-3 (1.5) a-4 (4) B-4 (100) — D-7 (0.75) E-2 (800) a-7 (1.5) Example 8A-1 (0.4) a-6 (8) B-4 (100) — D-5 (0.10) E-1 (240) D-6 (0.06) E-2 (560)D-7 (0.30) Example 9 A-2 (1.2) a-1 (0.5) B-5 (70) — D-1 (0.70) E-1 (240)a-5 (6.5) b-3 (30) E-2 (560) Example 10 A-4 (1) a-3 (1) B-5 (100) — D-5(0.75) E-1 (240) a-5 (5) E-2 (560) Example 11 A-1 (1.5) a-6 (6) B-6 (80)— D-2 (0.65) E-1 (240) b-4 (20) E-3 (560) Example 12 A-2 (2) a-3 (1) B-3(100) C-2 (5) D-2 (0.20) E-1 ((240) a-6 (5.5) D-3 (0.25) E-2 (560)Example 13 A-1 (1) a-2 (1.2) B-6 (100) — D-1 (0.40) E-1 (240) a-6 (6)D-2 (0.30) E-3 (560) Example 14 A-2 (0.6) a-3 (1) B-7 (70) — D-3 (0.20)E-1 (240) a-4 (5) b-2 (30) D-6 (0.15) E-2 (560) Comparative — a-2 (2)B-1 (65) — D-2 (0.70) E-2 (800) Example 1 a-4 (5) b-1 (35) Comparative —a-2 (3) B-4 (100) — D-1 (0.10) E-1 (240) Example 2 a-3 (4) D-5 (0.30)E-2 (560) Unit in parenthesis: part by weight

TABLE 2 PB PEB Temp Time Temp Time (° C.) (sec) Radiation (° C.) (sec)Example 1 90 90 KrF excimer laser 100 90 Example 2 90 60 KrF excimerlaser  90 60 Example 3 90 60 KrF excimer laser 100 60 Example 4 100  60excimer laser 110 60 Example 5 110  90 KrF excimer laser 110 90 Example6 90 60 KrF excimer laser 120 60 Example 7 100  60 KrF excimer laser 11560 Example 8 80 60 KrF excimer laser 100 90 Example 9 90 60 KrF excimerlaser  90 60 Example 10 100  60 KrF excimer laser 110 90 Example 11 9590 KrF excimer laser 110 90 Example 12 80 60 KrF excimer laser 100 90Example 13 110  60 Electron beam 110 60 Example 14 140  90 F2 excimerlaser 110 90 Comparative 100  90 KrF excimer laser 100 90 Example 1Comparative 90 90 KrF excimer laser 100 90 Example 2

TABLE 3 Sensitivity Resolution Nano-edge roughness Example 1 380 J/m²0.21 μm Good Example 2 420 J/m² 0.22 μm Good Example 3 380 J/m² 0.21 μmGood Example 4 370 J/m² 0.22 μm Good Example 5 370 J/m² 0.21 μm GoodExample 6 350 J/m² 0.21 μm Good Example 7 400 J/m² 0.22 μm Good Example8 390 J/m² 0.21 μm Good Example 9 370 J/m² 0.21 μm Good Example 10 380J/m² 0.21 μm Good Example 11 420 J/m² 0.22 μm Good Example 12 410 J/m²0.21 μm Good Example 13  5 μC/cm² 0.21 μm Good Example 14 160 J/m² 0.18μm Good Comparative 400 J/m² 0.22 μm Bad Example 1 Comparative 380 J/m²0.23 μm Bad Example 2

The radiation-sensitive resin composition of the present invention notonly exhibits excellent resolution performance and pattern-formingcapability, but also can suppress nano-edge roughness to a minimalextent. The composition therefore can be extremely useful as achemically-amplified resist for manufacturing semiconductor devices,which will become more and more micronized.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that, within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

1. A positive-tone radiation-sensitive resin composition comprising: (A)a photoacid generator which is a compound comprising a structure shownby the following formula (1-a) and a structure shown by the followingformula (1-b),

 wherein the groups R¹ to R¹⁵ individually represent a hydrogen atom, ahydroxyl group, a linear, branched, or cyclic alkyl group having 1-10carbon atoms, a linear, branched, or cyclic alkoxyl group having 1-10carbon atoms, or a t-butoxycarbonylmethoxy group, provided that two ormore of the groups R¹ to R⁵ are groups other than the hydrogen atom, twoor more of the groups R⁶ to R¹⁰ are groups other than the hydrogen atom,or two or more of the groups R¹¹ to R¹⁵ are groups other than thehydrogen atom; and the groups R¹⁶ to R²⁰ individually represent ahydrogen atom, fluorine atom, or trifluoromethyl group, provided that atleast one of the groups R¹⁶ to R²⁰ is a fluorine atom or trifluoromethylgroup, and (B) a resin comprising a recurring unit shown by thefollowing formula (2),

 wherein R²¹ represents a methyl group or ethyl group, and R²²represents a linear, branched, or cyclic alkyl group having 1-6 carbonatoms, and a recurring unit shown by the following formula (3)

wherein the structure represented by the formula (1-a) is at least onestructure selected from the group consisting of2,4-dimethylphenyldiphenylsulfonium cation,2,6-dimethylphenyldiphenylsulfonium cation,2,4,6-trimethylphenyldiphenylsulfonium cation,2,4,6-triethylphenyldiphenylsulfonium cation,2,4,6-tri-i-propylphenyldiphenylsulfonium cation,2,4-di-t-butoxyphenyldiphenylsulfonium cation,2,4-di-t-butoxycarbonylmethoxyphenyldiphenylsulfonium cation,4-t-butoxy-2,6-dimethylphenyldiphenylsulfonium cation, and4-t-butoxycarbonylmethoxy-2,6-dimethylphenyldiphenyl-sulfonium cation.2. The radiation-sensitive resin composition according to claim 1,wherein the structure represented by the formula (1-b) is at least onestructure selected from the group consisting of 4-fluorobenzenesulfonateanion, 2,4-difluorobenzenesulfonat anion, 2,6-difluorobenzenesulfonateanion, 2,3,4,5,6-pentafluorobenzenesulfonate anion,4-trifluoromethylbenzenesulfonate anion,2,4-bis(trifluoromethyl)benzenesulfonate anion,2,4,6-tris(trifluoromethyl)benzenesulfonate anion, and2,3,4,5,6-pentakis(trifluoromethyl)benzenesulfonate anion.
 3. Theradiation-sensitive resin composition according to claim 1, wherein thephotoacid generator is a compound selected from the group consisting of2,4-dimethylphenyldiphenylsulfonium2,3,4,5,6-pentakis(trifluoromethyl)benzenesulfonate,2,4,6-trimethylphenyldiphenylsulfonium 2,4-difluorobenzenesulfonate,2,4,6-trimethylphenyldiphenylsulfonium4-trifluoromethylbenzenesulfonate, 2,4,6-triethylphenyldiphenylsulfonium4-trifluoromethylbenzenesulfonate,2,4,6-tri-i-propylphenyldiphenylsulfonium 2,4-difluorobenzenesulfonate,4-t-butoxy-2,6-dimethylphenyldiphenylsulfonium2,3,4,5,6-pentafluorobenzenesulfonate, and4-t-butoxycarbonylmethoxy-2,6-dimethylphenyldiphenyl-sulfonium2,4,6-tris(trifluoromethyl)benzenesulfonate.
 4. The radiation-sensitiveresin composition according to claim 1, further comprising a photoacidgenerator other than the component (A).
 5. The radiation-sensitive resincomposition according to claim 4, wherein the photoacid generator otherthan the component (A) is at least one compound selected from the groupconsisting of onium salt compounds, sulfone compounds, sulfonatecompounds, sulfonimide compounds, diazomethane compounds, andoximesulfonate compounds.
 6. The radiation-sensitive resin compositionaccording to claim 4, wherein the photoacid generator other than thecomponent (A) is at least one compound selected from the groupconsisting of diazomethane compounds and oximesulfonate compounds. 7.The radiation-sensitive resin composition according to claim 1, whereinR²² in the formula (2) is a methyl group, ethyl group, or cyclohexylgroup.
 8. The radiation-sensitive resin composition according to claim1, wherein the recurring unit represented by the formula (2) is a unitobtained by cleavage of a polymerizable unsaturated bond in at least onecompound selected from the group consisting ofp-(1-methoxyethoxy)styrene, p-(1-ethoxyethoxy)styrene,p-(1-methoxypropoxy)styrene, p-(1-ethoxypropoxy)styrene, andp-(1-cyclohexyloxyethoxy)styrene.
 9. The radiation-sensitive resincomposition according to claim 1, wherein the resin (B) comprises arecurring unit other than the recurring units represented by the formula(2) or formula (3).
 10. The radiation-sensitive resin compositionaccording to claim 8, wherein the recurring unit other than therecurring units represented by the formula (2) or formula (3) is a unitobtained by cleavage of a polymerizable unsaturated bond in at least onecompound selected from the group consisting of styrene, α-methylstyrene,p-t-butoxystyrene, p-t-butoxycarbonyloxystyrene,p-t-butoxycarbonylmethyloxystyrene, p-acetoxystyrene,p-(2-butoxycarbonylethyloxy)styrene, t-butyl(meth)acrylate, isobornyl(meth)acrylate, tricyclodecanyl (meth)acrylate, 2-adamantyl-2-methyl(meth)acrylate, and 2-adamantyl-2-ethyl (meth)acrylate.
 11. Theradiation-sensitive resin composition according to claim 1, wherein theresin (B) is a resin having a structure partially cross-linked by across-linker.
 12. The radiation-sensitive resin composition according toclaim 1, wherein the number of the recurring units represented by theformula (2) in the resin (B) is 5-90% of the total number of therecurring units represented by the formula (2) and the recurring unitsrepresented by the formula (3).
 13. The radiation-sensitive resincomposition according to claim 1, further comprising an acid-dissociablegroup-containing resin other than the resin (B).
 14. Theradiation-sensitive resin composition according to claim 13, wherein theacid-dissociable group-containing resin other than the resin (B) is aresin insoluble or scarcely soluble in alkali having a structure inwhich the hydrogen atom of an acidic functional group in analkali-soluble resin having at least one recurring unit shown by thefollowing formulas (6) to (8) is replaced by a substituted methyl group,1-substituted ethyl group, 1-substituted propyl group, 1-branched alkylgroup, silyl group, germyl group, alkoxycarbonyl group, acyl group, orcyclic acid-dissociable group,

wherein R²⁶ represents a hydrogen atom or a methyl group, R²⁷ is ahalogen atom or an organic group having 1-6 carbon atoms, and n is aninteger of 0-3;

wherein R²⁸ represents a hydrogen atom or a methyl group; and


15. The radiation-sensitive resin composition according to claim 13,wherein the acid-dissociable group-containing resin other than the resin(B) is a resin insoluble or scarcely soluble in alkali having astructure in which the hydrogen atom of a phenolic hydroxyl group in analkali-soluble resin having at least one recurring unit shown by thefollowing formula (9) is replaced by a substituted methyl group,1-substituted ethyl group, 1-substituted propyl group, 1-branched alkylgroup, silyl group, germyl group, alkoxycarbonyl group, acyl group, orcyclic acid-dissociable group,

wherein R²⁹, R³⁰, R³¹, R³², and R³³ individually represent a hydrogenatom or a linear or branched alkyl group having 1-4 carbon atoms. 16.The radiation-sensitive resin composition according to claim 1, furthercomprising a dissolution controlling agent.
 17. The radiation-sensitiveresin composition according to claim 16, wherein the dissolutioncontrolling agent is a compound shown by one of the following formulas(10)-(14):

wherein R³⁴ groups individually indicate a hydrogen atom or anacid-dissociable substituent, R³⁵ groups individually represent a linearor branched alkyl group having 1-4 carbon atoms, a phenyl group, or a1-naphthyl group, p is an integer of 1 or more, and q is an integer of 0or more, provided that p+q≦6;

wherein R³⁴ and R³⁵ are the same as defined for the above formula (10),and A represents —O—, —S—, —CO—, —COO—, —SO—, —SO₂—, —C(R³⁶)(R³⁷)—,wherein R³⁶ and R³⁷ individually represent a hydrogen atom, a linear,branched, or cyclic alkyl group having 1-6 carbon atoms, an acyl grouphaving 2-11 carbon atoms, a phenyl group, or a 1-naphthyl group, or agroup shown by the following formula,

wherein R³⁵ is the same as defined above and x is an integer of 0-4, andp, q, r, and s are integers of 0 or more, provided that p+q≦5, r+s≦5,and p+r≧1 are satisfied;

wherein R³⁴ and R³⁵ are the same as those defined in the formula (10),R³⁸ represents a hydrogen atom, a linear or branched alkyl group having1-4 carbon atoms, or a phenyl group, and p, q, r, s, t, and u areintegers of 0 or more, provided that p+q≦5, r+s≦5, t+u≦5, and p+r+t≧1are satisfied;

wherein R³⁴ and R³⁵ are the same as defined for the above formula (10),A is the same as defined in the above formula (11), R³⁸ is the same asdefined in the formula (12), provided that when two or more R³⁸ groupsas present, such groups may be either identical or different, and p, q,r, s, t, u, v, and w are integers of 0 or more, provided that p+q≦5,r+s≦5, t+u≦5, v+w≦5, and p+r+t+v≧1 are satisfied; and

wherein R³⁴ and R³⁵ are the same as defined for the above formula (10),R³⁸ is the same as defined in the formula (12), provided that when twoor more R³⁸ groups are present, such groups may be either identical ordifferent, and p, q, r, s, t, u, v, and w are integers of 0 or more,provided that p+q≦5, r+s≦5, t+u≦5, v+w≦4, and p+r+t+v≧1 are satisfied.18. The radiation-sensitive resin composition according to claim 1,further comprising an acid diffusion controller.
 19. Theradiation-sensitive resin composition according to claim 18, wherein theacid diffusion controller is a nitrogen-containing organic compound. 20.The radiation-sensitive resin composition according to claim 1,comprising at least one compound from the group consisting of propyleneglycol mono-alkyl ether acetates, lactic acid esters, 3-alkoxypropionicacid esters, 2-heptanone, and cycloheptanone.
 21. A positive-toneradiation-sensitive resin composition comprising: (A) a photoacidgenerator which is a compound comprising a structure shown by thefollowing formula (1-a) and a structure shown by the following formula(1-b),

 wherein the groups R¹ to R¹⁵ individually represent a hydrogen atom, ahydroxyl group, a linear, branched, or cyclic alkyl group having 1-10carbon atoms, a linear, branched, or cyclic alkoxyl group having 1-10carbon atoms, or a t-butoxycarbonylmethoxy group, provided that two ormore of the groups R¹ to R⁵ are groups other than the hydrogen atom, twoor more of the groups R⁶ to R¹⁰ are groups other than the hydrogen atom,or two or more of the groups R¹¹ to R¹⁵ are groups other than thehydrogen atom; and the groups R¹⁶ to R²⁰ individually represent ahydrogen atom, fluorine atom, or trifluoromethyl group, provided that atleast one of the groups R¹⁶ to R²⁰ is a fluorine atom or trifluoromethylgroup, and (B) a resin comprising a recurring unit shown by thefollowing formula (2),

 wherein R²¹ represents a methyl group or ethyl group, and R²²represents a linear, branched, or cyclic alkyl group having 1-6 carbonatoms, and a recurring unit shown by the following formula (3)

 wherein the photoacid generator is a compound selected from the groupconsisting of 2,4-dihydroxyphenyldiphenylsulfonium2,4,6-tris(trifluoromethyl)benzenesulfonate,2,4-dimethylphenyldiphenylsulfonium2,3,4,5,6-pentakis(trifluoromethyl)bezenesulfonate,2,4,6-trimethylphenyldiphenylsulfonium 2,4-difluorobenzenesulfonate,2,4,6-trimethylphenyldiphenylsulfonium4-trifluoromethylbenzenesulfonate, 2,4,6-triethylphenyldiphenylsulfonium4-trifluoromethylbenzenesulfonate,2,4,6-tri-i-propylphenyldiphenylsulfonium 2,4-difluorobenzenesulfonate,4-t-butoxy-2,6-dimethylphenyldiphenylsulfonium2,3,4,5,6-pentafluorobenzenesulfonate, and4-t-butoxycarbonylmethoxy-2,6-dimethylphenyldiphenyl-sulfonium2,4,6-tris(trifluoromethyl)benzenesulfonate.